which of the following are valid probability distribution for a discrete random variable? Check all that apply. A 1/5,1/5,1/5,1/5,1/5 B -1/2,-1/3,-1/4,-1/5,137/60 C 1/12,1/12,1/12,1/12,1/6,1/12,1/12,1/12,1/12,1/6 D 1/2,1/4,1/8,1/16,1/32,1/64,1/128,1/127 E 1/6,1/5,1/4,1/3