单选题 The babies Would "smile and bubble" at the lights because ______.

A、 they succeeded in "switching on" the light
B、 the sight of the lights was interesting
C、 they need not turn back to watch the lights
D、 the lights were directly related to some basic "drives”

【正确答案】 A

【答案解析】婴儿们冲着灯微笑或笑出声是因为：A．“他们成功地把灯“打开”了”；B．“看灯很有趣”：C．“他们不必转过去看灯了”；D．“灯光与某些基本本能有直接关联”。第四段Papousek得出这样的结论，并不是灯本身使他们那么高兴，而是由于他们成功地解决了这个问题，掌握了这一技巧，所以A为正确答案。