Suppose host A is sending to a multicast group; the recipients are leaf nodes of a tree rooted at A with depth N and with each nonleaf node having k children; there are thus k^N recipients.

(a) How many individual link transmissions are involved if A sends a multicast message to all recipients?

(b) How many individual link transmissions are involved if A sends unicast messages to each individual recipient?

(c) Suppose A sends to all recipients, but some messages are lost and retransmission is necessary. Unicast retransmissions to what fraction of the recipients is equivalent, in terms of individual link transmissions, to a multicast retransmission to all recipients?