VideoStream/Multicast Direct

B.

The VideoStream/Multicast Direct feature is a Cisco wireless feature that enables reliable delivery of video multicast traffic over the wireless network. With this feature, video multicast traffic is converted to unicast frames and then transmitted over the wireless network.

Regarding the options:

A. The IEEE 802.11 wireless multicast delivery mechanism defines how multicast traffic is delivered over the wireless network. However, this delivery mechanism is not always reliable, especially in high-density environments or environments with a lot of interference.

B. This statement is not true. The VideoStream/Multicast Direct feature does not require clients to acknowledge receipt of a video multicast stream.

C. This statement is partly true. The VideoStream/Multicast Direct feature converts multicast traffic to unicast frames to enable reliable delivery over the wireless network. However, it does not convert unicast frames to multicast frames.

D. This statement is not true. The VideoStream/Multicast Direct feature is designed to improve the reliability of IP multicast stream delivery over the wireless network. It does not make delivery less reliable over the air, but rather more reliable by converting multicast traffic to unicast frames.

In summary, the correct answer is C: "It converts the unicast frame to a multicast frame over the air" is an incorrect statement about the VideoStream/Multicast Direct feature.