1) a) At low load, pure ALOHA performs better than slotted ALOHA in terms of packet delay "- Refute or validate the statement. [2] b) Why does WLANs not use CSMA/CD-give 2 reasons. 2] c What problem does the MACA protocol address in WLANs? Name the mechanism by which it solves the problem? [2] d) A 802.11 wireless device has two carrier sensing mechanisms implemented - name them. [2]