Probe requests will contain data rate information, but I disagree on whether or not a STA can determine that from the probe requests of OTHER STAs. I believe that in this case, the correct answer is A. Beacon frames actually do provided supported data rates. It is 8 octet field where each octet describe a single supported rate. Last bit (7th) of each octet indicate whether the data rate is “basic rate or mandatory” or “supported rate”. If 7th bit value is 1 it indicate a basic rate where as if value is 0 indicate a supported rate. The next 7 bit (0-6) specify the data rate value in units of 500kbps

Answer is A. The probe request frame is transmitted by a (client) STA to the AP, and will only indicate the data rate information relating to that STA, ie it tells the AP what data rate the client in question supports. This has no bearing with the data rate that the AP and other client STAs support. The only means for any client STA to know the data rate supported by the AP is through either: 1. the BEACON sent by the AP or 2. a PROBE RESPONSE sent by the AP in reply to a probe request

Beacon Frames and Probe Responses both contain information about supported data rates from the AP. I don't think it is D because 1: It mentions problem requests (Not responses) and 2: They are from other clients which wont tell you anything about the AP data rates.

I am sorry I was wrong about the answer. It is indeed probe request frames that have supported data rate information.

The correct answer is A. As the beacon frames are for passive scanning.