. The sum of the probabilities of all elementary events of an experiment is p, then
(a) 0 < p < 1
(b) 0 ≤ p < 1
(c) p = 1
(d) p = 0
. The sum of the probabilities of all elementary events of an experiment is p, then
(a) 0 < p < 1
(b) 0 ≤ p < 1
(c) p = 1
(d) p = 0