An HR-DSSS STA does not receive an ACK for a first-attempt data frame that it transmitted. In this case, what happens to the STA’s DCF contention window?

A.
The slot time within the contention window decreases by 50%.

B.
It varies because the backoff algorithm is random.

C.
The contention window approximately doubles in size.

D.
The contention window is not affected by failed Data frame deliveries.

E.
The contention window is immediately closed, and the frame is retransmitted.