Answer:
They usually cannot grow again
Explanation:
Growing muscle, or you haven’t been used to doing leg exercises
After World War II, Americans shifted to more service and agricultural jobs in a way, they decided that they should be more self-sufficient in terms of agronomy, but more importantly, they turned towards service with the rise of consumerism. Consumerism in America greatly dictated how the country has progressed in the past few decades.
B is the right answer for that reason.
It seems to me that there is no negative or positive correlation. It looks nonlinear if you ask me.