单选题 The electric catfish has a different electric system in that

A、 current moves from the head to the tail.
B、 current moves from the tail to the head.
C、 current moves from the left to the right.
D、 current moves from the right to the left.

【正确答案】 B

【答案解析】[解析]由文章倒数第二段第一句“The electric catfish of the Nile and of other African fresh waters has a different system again by which current passes over the whole body from the tail to the head．”可知答案为B。故应选B。