With the influence of the financial crisis ,only two people came to look at the house,_____ wanted to buy it.

A．neither of them

B．both of them

C．none of whom

D．neither of whom

如果对某活动工期的天数进行估算，乐观=5，悲观=7，最有可能=4，活动的标准偏差是？（）

A.5天

B.2天

C.1/3天

D.1/4天