The FortiGate 6000F has 24 1/10/25-Gbps SFP28 data network interfaces (1 to 24). These interfaces are divided into the following interface groups: 1 to 4, 5 to 8, 9 to 12, 13 to 16, 17 to 20, and 21 to 24. The ports 25 to 28 are 40/100-Gbps QSFP28 data network interfaces.
The initial connection should be made to any interface between ports 1 to 4. This is because the ports 21 to 24 are part of the same interface group, and changing the speed of one of these ports will affect the speeds of all of the ports in the group. The ports 5 to 8 are also part of the same interface group, so they should not be used for the initial connection.
The new hardware module that will be installed in the switch will provide higher speed ports. When this module is installed, the speed of the ports 21 to 24 will be increased. However, this will not affect the ports 1 to 4, because they are not part of the same interface group.
Therefore, the initial connection should be made to any interface between ports 1 to 4, in order to ensure that the FortiGate interface connected to the switch does not affect any other port when the new module is installed and the new port speed is defined.
Reference:
FortiGate 6000F Front Panel Interfaces: https://docs.fortinet.com/document/fortigate-6000/hardware/fortigate-6000f-system-guide/827055/front-panel-interfaces

D is correct because Spoke1 will establish an ADVPN shortcut to Spoke2 when it detects that there is a demand for traffic between them. This is explained in the Fortinet Community article on Technical Tip: Fortinet Auto Discovery VPN (ADVPN) under Summary - ADVPN sequence of events. Reference: https://community.fortinet.com/t5/FortiGate/Technical-Tip-Fortinet-Auto-Discovery-VPN-ADVPN/ta-p/195698

https://docs.fortinet.com/document/fortigate/7.0.1/administration-guide/834664/route-leaking-between-vrfs- with-bgp

The FEC configuration in the exhibit specifies that if the packet loss is greater than 10%, then the FEC mapping will be 8 base packets and 2 redundant packets. The download bandwidth of 500 Mbps is not greater than 950 Mbps, so the FEC mapping is not overridden by the bandwidth setting. Therefore, the FEC behavior will be 2 redundant packets for every 8 base packets.
Here is the explanation of the FEC mappings in the exhibit:
Packet loss greater than 10%: 8 base packets and 2 redundant packets.
Upload bandwidth greater than 950 Mbps: 9 base packets and 3 redundant packets.
The mappings are matched from top to bottom, so the first mapping that matches the conditions will be used. In this case, the first mapping matches because the packet loss is greater than 10%. Therefore, the FEC behavior will be 2 redundant packets for every 8 base packets.