Question

In a communication network, a packet of length L bits takes link L1 with a probability of p1 or link L2 with a probability of p2. Link L1 and L2 have bit error probability of b1 and b2 respectively. The probability that the packet will be received without error via either L1 or L2 is

(A) p1*(1-b1)^L+p2*(1-b2)^L
(B) [1-(b1+b2)^L]*p1*p2
(C) (1—b1 )^L * (1 —b2 )^L *p1 * p2
(D) 1 —(p1*b1^L+p2*b2^L)