The Existence of Workers Among Honey Bees and Other Eusocial

The existence of workers among honey bees and other eusocial insects is considered a Darwinian puzzle because

A) these workers are largely sterile and so should be eliminated over time by natural selection.
B) Darwin felt that the self-sacrificing behavior of these insects could not be explained by the theory of group selection.
C) the self-sacrificing workers do not live as long as the queens of the same species of eusocial insects.
D) queens with a large worker force produce more reproductive sons and daughters than those with a small worker force.