If X∼Binomial(n,p)X \sim \text{Binomial}(n, p)X∼Binomial(n,p), which expression represents the probability generating function GX(s)=E[sX]G_X(s) = E[s^X]GX(s)=E[sX]?
(ps+1−p)n(ps + 1 - p)^n(ps+1−p)n
(p+(1−p)s)n(p + (1-p)s)^n(p+(1−p)s)n
en(s−1)e^{n(s-1)}en(s−1)
pnsnp^n s^npnsn