What must be considered when using 802.11a?

What must be considered when using 802.11a?

A. It is chosen over 802.11b when a lower-cost solution is necessary B. It is susceptible to interference from 2.4 GHz devices such as microwave ovens C. It is compatible with 802.11b- and 802 11g-compliant wireless devices D. It is used in place of 802.11b/g when many nonoverlapping channels are required