The correct option is B Both a and b
Cyclone and anticyclone are two important types of cyclonic activity. The atmospheric disturbance which involves a closed circulation about a low-pressure center, anticlockwise in the northern hemisphere and clockwise in the southern hemisphere, are called cyclones. On the other hand, anticyclone plays a much less important role in the weather-drama at the surface of the earth in comparison with the cyclone. It denotes on atmospheric system that is just opposite of the cyclonic system.