单选题 The author believes that the reaction of an unborn baby to his mother' s voice

A、 belongs to one of the natural tendencies
B、 is an indication which shows an unborn baby can use all his senses after birth
C、 is but a physiological circulation of any human being
D、 is the most important factor which leads an unborn baby to the survival in the womb

【正确答案】 C

【答案解析】从第二段中作者对于婴儿对父亲的声音没有天生的兴趣的解释，即由于母亲的声音无时无刻不在那儿，和最后一段婴儿对于tress-related hormones的反映的描述来看，作者应该认为这只是一种生理现象。故答案为C。其他选项在文中都没有体现。