What is the most likely cause of this problem?

Your customer’s 802.11n laptops are not able to see the SSID in the 5 GHz band in the conference room. When doing a walkthrough using one of these laptops, you confirm that it is unable to see the SSID in the 5 GHz band in the conference room. When using your own 802.11 ac laptop, you’re able to see the SSID.

What is the most likely cause of this problem?
A . The AP is configured to use channel 36
B . The customer laptop does not support Transmit Beamforming
C . The AP is on channel 144
D . Their laptops are SISO clients

Answer: B