题目

Luciano Baietti, a retired school, headmaster from Italy, holds the Guinness record for the most university degrees. The 70-year-old currently has 15 bachelors or masters degrees from various universities across Italy, and is getting ready to get his 16th. Getting more than one college degree is not exactly unheard of, but 15 is apparently quite impressive, since it’s only been done by one man. Although he spends his days working around his house and garden, like most people his age, at night, Baretti turns into n student again. Every morning, at 3 a. m., when most of the world is sle袋中有大小相同的5个白球和3个黑球，从中任意摸出4个，则摸出2个或3个白球的概率为（　　）A．67B．47C．37D．27