During transmission over a communication channel, bit errors occur independently with probability p. If a block of $n$ bits is transmitted, the probability of at most one bit error is equal to
- $1-(1-p)^n$
- $p+(n-1)(1-p)$
- $n p(1-p)^{n-1}$
- $(1-p)^{n}+ n p(1-p)^{n-1}$