The babies would" smile and bubble" at the lights because ______.A．the lights were directl

The babies would" smile and bubble" at the lights because ______.

A．the lights were directly related to some basic" drives"

B．the sight of the lights was interesting

C．they need not turn back to watch the lights

D．they succeeded in "switching on" the lights

请帮忙给出正确答案和分析，谢谢！