[-π/2,0]
[0,π/2]
[0,π]
[0,3π/2]
此题，根据概率密度的性质，要求f(x)在区间[a,b]上的积分为1，且f(x)在区间[a,b]上大于等于0.
由此可见B项满足两个条件，故答案为B.
