Some birds are pollinators that co-evolved with plants, and hummingbirds are an important groups of bird pollinators. Given these facts, what co-evolved with plants among the following options:
- gravity
 - peachleaf willow
 - Chemical energy
 - Organic compounds
 - hummingbirds
 - h2o
 - density
 - animals


 

     hummingbirds    