下列现象中，不属于动物行为的是[ ]

A．公鸡打鸣

B．小鸟喂鱼

C．小猴表演节目

D．小狗长牙

The girl had hardly rung the bell ___ the door was opened suddenly, and out rushed her friend. [ ]

A. before          

B. when            

C. until            

D. since