—Why isn't Lucy here with you?

—Her mother's ill and she has to _________ her little sister at home. [ ]

A. look after

B. look at

C. look around

D. look for

某超市的某种饮料的日需求量为1000罐，提前期随机变化且服从均值为5天，标准差为l天的正态分布，如果该超市确定的客户服务水平要达到95％，请结合所提供的客户服务水平与安全系数对应关系的常用数据（见下表），计算出该种饮料的安全库存量是多少。