When a host fails to obtain an IP address from a DHCP server, it assigns itself an APIPA (Automatic Private IP Addressing) address in the 169.254.x.x range, commonly described as a "self-assigned IP." This prevents communication outside the local link, including reaching the default gateway.
* B. RFC1918 addresses are private ranges (10.x.x.x, 172.16-31.x.x, 192.168.x.x), but these are not self- assigned.
* C. If the TCP/IP stack were disabled, the host wouldn't have any IP at all.
* D. If a static IP were assigned, it would show a configured value, not self-assigned.
References (CompTIA Network+ N10-009):
* Domain: Network Troubleshooting - IP addressing issues, DHCP failures, APIPA behavior.

If the IP phone works but the workstation doesn't, it indicates that theVoice VLAN is functioningcorrectly, but theData VLAN (C)is either misconfigured or missing. The workstation typically connects through the phone, which tags voice and data traffic separately usingVLANs.
* A. Voice VLANis for the IP phone, which is already working.
* B. Native VLANis for untagged traffic on trunk ports, but doesn't control access directly.
* D. Trunk portis more relevant to switch interconnections than individual workstation ports.
#Reference:
CompTIA Network+ N10-009 Official Objectives: 2.3 - Given a scenario, configure and verify VLANs.

When a new VLAN is created, it typically exists on a different subnet. If DHCP servers are on a different VLAN, the network needs an IP helper address to forward DHCP requests correctly.
Without it, clients in the new VLAN won't receive an IP address.

See the answer and solution below
Explanation:

The correct answer is A. Channel overlap . The signal strength numbers given, -50 to -65 dBm , are generally strong enough for normal client connectivity, so this does not point to weak coverage. The bigger clue is that the environment is a multitenant office building and the wireless network is using 2.4 GHz .
That band is well known for congestion and overlapping channels, especially where many nearby businesses or tenants have their own access points.
In the 2.4 GHz range, there are only a few non-overlapping channels commonly used. When many APs operate close together on overlapping channels, clients can experience interference, retransmissions, poor throughput, buffering, and connection instability. Those symptoms fit the scenario very well.
The other options are less convincing. Insufficient wireless coverage does not line up with the reported signal levels. AP antenna type could matter in some designs, but there is nothing in the question pointing to a directional or placement issue. WPA2 is not the cause of the performance symptoms here; while it is older than WPA3, it does not normally create repeated buffering and disconnections in this way.
This is really a wireless interference question, and in a crowded 2.4 GHz building, channel overlap is the most likely reason.