plz solve this problem in detail

Consider a random variable X that takes values +1 and -1 with probability 0.5 each. The values of cumulative distribution function F(X) at x=-1 and +1 are....?

(A) 0 and 0.5 (B) 0 and 1 (C) 0.5 and 1 (D) 0.25 and 0.75