How Did the Deaths of Millions of Indians by the End

How did the deaths of millions of Indians by the end of the sixteenth century affect Spain?

A) The Spanish believed Indians to be inferior so their demise was no great loss.
B) The Spaniards realized the value of germ warfare and used it in the future.
C) The deaths created a labor shortage that led to the purchase of African slaves.
D) The Spanish exhausted all natural resources in the areas they had colonized.