The correct answer is: B. Antenna diversity.
Space diversity is a technique used to improve the reliability of a wireless communication system by using multiple antennas at the transmitter and receiver. This helps to reduce the effects of fading, which is a loss of signal strength caused by changes in the environment.
Frequency diversity is a technique used to improve the reliability of a wireless communication system by using multiple frequencies. This helps to reduce the effects of interference, which is a degradation of signal quality caused by other signals.
Polarization diversity is a technique used to improve the reliability of a wireless communication system by using multiple polarizations. This helps to reduce the effects of multipath fading, which is a loss of signal strength caused by the signal reflecting off of multiple objects.
Time diversity is a technique used to improve the reliability of a wireless communication system by using multiple time slots. This helps to reduce the effects of intersymbol interference, which is a degradation of signal quality caused by the signal overlapping with itself.
In conclusion, space diversity is a technique used to improve the reliability of a wireless communication system by using multiple antennas. This helps to reduce the effects of fading, which is a loss of signal strength caused by changes in the environment.