all their lives 和their whole lives有区别吗?

题目

all their lives 和their whole lives有区别吗?
In the area where Wang Lung,his father and his father's father had lived__________,there were famines once in five years.
A.all their lives B.their whole lives 答案选A而不选B,为什么呢?

答案

A表示的是他们的生命,B表示的是他们生命的全部,就是一点点差别,就是说后面一个表示他们一生本身,而第一个是说两代人的人生.