—Which driver was to blame?

　　—Why, ____! It was the child’s fault, clear and simple. He suddenly came out between two parked cars.

A．both

B．each

C．either

D．neither

为什么有了菩提心的摄持，我们平时积累的念佛、放生等善根就永不会穷尽？请结合比喻说明。