Fact 1: Some birds are pollinators that co-evolved with plants.

Fact 2: Hummingbirds are an important groups of bird pollinators.

Given the two facts above, answer the question "what co-evolved with plants?" with the following options: 
- gravity
 - peachleaf willow
 - Chemical energy
 - Organic compounds
 - hummingbirds
 - h2o
 - density
 - animals


 

     hummingbirds    