单选题 The terms wad and frog refer to two different animals belonging to different genuses, and careful students ______ the two.

【正确答案】 C
【答案解析】(distinguish区分)。句意为：蟾蜍和青蛙指具有不同特征的两种截然不同的动物，细心的学生能将二者区分开来。A．intermingle使混合；B．ignore忽视；D． confuse混淆。