Which statement about the VideoStream/Multicast Direct feature is true?

Which statement about the VideoStream/Multicast Direct feature is true?
A . IP multicast traffic is reliable over WLAN by default as defined by the IEEE 802.11 wireless multicast delivery mechanism.
B . Each VideoStream client acknowledges receiving a video IP multicast stream.
C . It converts the unicast frame to a multicast frame over the air.
D . It makes the delivery of the IP multicast stream less reliable over the air, but reliable over Ethernet.

Answer: B