单选题 ______ with the truth in small matters cannot be trusted with important matters.
A. No matter who is careless B. Whoever is careless
C. He is careless D. As is careless

【正确答案】 B
【答案解析】[解析] 关系代词用法辨析
小事马虎，大事不稳。本句需要由whoever引导主语从句，并在主语从句中作主语。