Which one of the following portions of information is communicated by bits in the PHY...

One of the information that is communicated by bits in the PHY header is data rate. Data rate is the speed at which data is transmitted or received over the wireless medium. Data rate depends on factors such as modulation, coding, channel width, spatial streams, and guard interval. Data rate is indicated by bits in different fields of the PHY header, depending on the type of PPDU (e.g., OFDM, HT, VHT, HE). The receiver uses these bits to determine how to decode and demodulate the rest of the PPDU. The other options are not correct, as they are not communicated by bits in the PHY header. SNR (Signal-to-Noise Ratio), noise, and signal strengthare measured by the receiver based on its own capabilities and environment. References: [Wireless Analysis Professional Study Guide CWAP-404], Chapter 4: 802.11 Physical Layer, page 101-105