What is the Cisco-recommended signal-to-noise ratio for a data rate of 54 Mbps on a 5-GHz data network?

What is the Cisco-recommended signal-to-noise ratio for a data rate of 54 Mbps on a 5-GHz data network?

A.
25 dB

B.
30 dB

C.
35 dB

D.
40 dB