题目:若随机变量X服从二项分布B(n, p),且E(X) = 3.5,D(X) = 3.15,则参数n和p的值分别为:A. n=7, p=0.5 B. n=10, p=0.35 C. n=7, p=0.35 D. n=10, p=0.5