During transmision over a communication channel, bit errors occur independly with probability p. If a block of n bits is transmitted, the probability of atmost one bit error is equal to

a) 1 - (1 - p)ⁿ

b) p + (n - 1) (1 - p)

c) np (1 - p)^{n - 1}

d) (1 - p)ⁿ + np (1 - p)^{n -1}

Ans ; (1 - p)ⁿ + np (1 - p)^{n -1}