Final answer:
The technique used in 802.11g Access Points (APs) to reduce the possibility of collisions when legacy 802.11b devices are within range is known as CTS-to-Self (Clear To Send).
Therefore, the correct answer is: option c). CTS-to-Self
Step-by-step explanation:
CTS-to-Self is used strictly as a protection mechanism for mixed-mode environments. This technique helps minimize coexistence issues between the different standards.
When an 802.11g AP has to communicate with an 802.11b device, it uses CTS-to-Self to essentially reserve the air time for the transmission, alerting other devices to hold off from transmitting during this period, reducing the likelihood of data collisions.
One of the benefits of using CTS-to-Self over RTS/ CTS as a protection mechanism is that the throughput will be higher because fewer frames are being sent. It is important to make sure that all stations hear the CTS to reserve the medium, and this is most likely to occur if it is being sent by an AP.
If a client station were to use CTS-to-Self, there is a chance that another client station on the opposite side of the BSS might be too far away from the CTS-to-Self and would not realize that the medium is busy.