The answer is going to be D
Students would be the subject because they are the ones doing the action. Questions is the direct object, and Elsa is the indirect object
A.People in both places were introduced to new crops and animals.
B.Millions of Native Americans moved to Europe and assimilated into European society.
C.Many Europeans were enslaved and taken to North and South America.
hope this helps !!
You can eliminate "B" is not "A" neither. "C" I don't think they have to be complete thoughts as long as they make sense. So I think I will go with "D" hope it helps.
It suggests that the heat has real power to change its environment