I believe it is D. More African elephants today naturally lack tusks compared to the elephant populations 100 years ago, because big game hunters sought elephants for ivory.
Humans can will themselves to eat more, as we know that food comes easy to us.
Animals, on the other hand, top priority is survival, so they usually wouldn't think about eating more because it just "tastes good."
Any cells of the human body, except the cells of a placenta.
Darwin finally consolidated all of his observations into his famous book
On The Origin of Species, drastically and controversially altering the
scientific view on the biological origins of life. I learned this a little while ago in my school, I kept notes!! Hope this helps!! <3