You are presented with the quiz "Hummingbirds are what they are today as a necessary consequence of their relationship to what?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "some birds are pollinators that co-evolved with plants" and "hummingbirds are the most common bird pollinators". 

So, what's the best answer to the question?


 

      Plants     