单选题 Although he has had no formal education, he is one of the ______ businessmen in the company.
【正确答案】 A
【答案解析】shrewd精明的；stern严格的；nasty难受的，令人不快的；alert(to)有警惕的，机敏的。句意：虽然他没有受过正规教育，但他却是公司里最精明的商人之一。