The correct answer is /25, which is the appropriate subnet mask for dividing an existing Class C network into two equal subnets. According to the CompTIA Network+ N10-009 objectives, subnetting is a core networking concept used to improve network segmentation, performance, and security.
A Class C network uses a default subnet mask of /24 (255.255.255.0), which provides 256 total addresses (254 usable). To split this network into two sections, the administrator must borrow one host bit from the last octet. Borrowing one bit results in a /25 subnet mask (255.255.255.128). This creates two subnets, each with
128 total addresses (126 usable)-an ideal solution for separating two departments such as finance and marketing.
A /24 would not create any segmentation, as it represents the original single network. A /26 would create four subnets, and a /27 would create eight subnets, both of which exceed the requirement of only two sections and unnecessarily reduce the number of available host addresses per subnet.
The Network+ objectives emphasize selecting subnet masks based on organizational requirements, balancing the number of subnets with sufficient host capacity. In this scenario, /25 is the most efficient and correct choice.

An active-passive approach keeps a standby environment available to take over when the primary data center fails, allowing services to be restored and accessed quickly after a disaster.

Comprehensive and Detailed Explanation (paraphrased, aligned to N10-009):
In a spine-leaf architecture, endpoints (including servers, firewalls, and WAN/edge routers) connect to leaf switches. Leaf switches then uplink to spine switches; spine switches do not have endpoints connected directly to them. Therefore, a WAN router (an external/edge device) should connect to the leaf layer-often specifically to a "border leaf" that handles external connectivity.
Why not B. Core or D. Spine? In spine-leaf, "core" isn't a formal layer, and spines are designed only to interconnect leafs, not to terminate endpoints.
Why not A. Access? "Access" is a term from the traditional three-tier model (access-distribution-core). In modern spine-leaf language, the analogous layer for endpoint attachment is the leaf.
Reference (CompTIA Network+ N10-009):

See the solution below in Explanation.
Explanation:
To provide a complete solution for configuring the access layer switches, let's proceed with the following steps:
* Identify the correct VLANs for each device and port.
* Enable necessary ports and disable unused ports.
* Configure fault-tolerant connections between the switches.
Port 1 Configuration (Uplink to Core Switch)
* Status: Enabled
* LACP: Enabled
* Speed: 1000
* Duplex: Full
* VLAN Configuration: Tagged for VLAN60, VLAN90, VLAN120, VLAN150, VLAN220 Port 2 Configuration (Uplink to Core Switch)
* Status: Enabled
* LACP: Enabled
* Speed: 1000
* Duplex: Full
* VLAN Configuration: Tagged for VLAN60, VLAN90, VLAN120, VLAN150, VLAN220 Port 3 Configuration (Server Connection)
* Status: Enabled
* LACP: Disabled
* Speed: 1000
* Duplex: Full
* VLAN Configuration: Untagged for VLAN90 (Servers)
Port 4 Configuration (Server Connection)
* Status: Enabled
* LACP: Disabled
* Speed: 1000
* Duplex: Full
* VLAN Configuration: Untagged for VLAN90 (Servers)
Port 5 Configuration (Wired Users and WLAN)
* Status: Enabled
* LACP: Enabled
* Speed: 1000
* Duplex: Full
* VLAN Configuration: Tagged for VLAN60, VLAN120, VLAN150
Port 6 Configuration (Wired Users and WLAN)
* Status: Enabled
* LACP: Enabled
* Speed: 1000
* Duplex: Full
* VLAN Configuration: Tagged for VLAN60, VLAN120, VLAN150
Port 7 Configuration (Voice and Wired Users)
* Status: Enabled
* LACP: Enabled
* Speed: 1000
* Duplex: Full
* VLAN Configuration: Tagged for VLAN60, VLAN90, VLAN120, VLAN220
Port 8 Configuration (Voice, Printers, and Wired Users)
* Status: Enabled
* LACP: Enabled
* Speed: 1000
* Duplex: Full
* VLAN Configuration: Tagged for VLAN60, VLAN90, VLAN120, VLAN220
Port 1 Configuration (Unused)
* Status: Disabled
* LACP: Disabled
Port 2 Configuration (Unused)
* Status: Disabled
* LACP: Disabled
Port 3 Configuration (Connection to Device)
* Status: Enabled
* LACP: Disabled
* Speed: 1000
* Duplex: Full
* VLAN Configuration: Untagged for VLAN1 (Default)
Port 4 Configuration (Connection to Device)
* Status: Enabled
* LACP: Disabled
* Speed: 1000
* Duplex: Full
* VLAN Configuration: Untagged for VLAN1 (Default)
Port 5 Configuration (Connection to Device)
* Status: Enabled
* LACP: Disabled
* Speed: 1000
* Duplex: Full
* VLAN Configuration: Untagged for VLAN1 (Default)
Port 6 Configuration (Connection to Device)
* Status: Enabled
* LACP: Disabled
* Speed: 1000
* Duplex: Full
* VLAN Configuration: Untagged for VLAN1 (Default)
Port 7 Configuration (Connection to Device)
* Status: Enabled
* LACP: Disabled
* Speed: 1000
* Duplex: Full
* VLAN Configuration: Untagged for VLAN1 (Default)
* Ports 1 and 2 on Switch 1 are configured as trunk ports with VLAN tagging enabled for all necessary VLANs.
* Ports 3 and 4 on Switch 1 are configured for server connections with VLAN 90 untagged.
* Ports 5, 6, 7, and 8 on Switch 1 are configured for devices needing access to multiple VLANs.
* Unused ports on Switch 3 are disabled.
* Ports 3, 4, 5, 6, and 7 on Switch 3 are enabled for default VLAN1.
* Core Switch Ports should be configured as needed for uplinks to Switch 1.
* Ensure LACP is enabled for redundancy on trunk ports between switches.
By following these configurations, each device will access only its correctly associated network, unused switch ports will be disabled, and fault-tolerant connections will be established between the switches.

In the route selection process, a router first prioritizes the route with the longest prefix length, as it represents the most specific match for a destination address.