What makes the 'avunculate' such a clever cultural invention?
A. It focuses the bachelor (unmarried, child-free) uncle's energy on his sibling's children, perpetuating the family's genes
B. It focuses a man's energy on offspring that he knows are in his bloodline.
C. It saves men from the hard work that fatherhood entails.
D. It focuses the spinster (unmarried, child-free) aunt's energy on her sibling's children, perpetuating the family's genes.
E. It keeps men from siring or having too many children.