Assuming that channel f_i ≠ f_j for i ≠ j , determine whether there can be a collision and an interference in Problem P15.10 if 

(a) Group (A, B, C, and D) or Group (E, F, G, and H) are simultaneously operating due to overlapping of memberships between these groups.
(b) All eight groups are communicating simultaneously.
(c) Any six groups are operational at a time due to limitations on the availability of laptops.