Farms productivey and native ecosystem
I'm pretty sure it would be D... If that's wrong I'm sorry.
Lots of hand waving as is in the current field of much of molecular biology. Other than that experiments and observations. Basically the utilization of the scientific method and then trying to find the mechanism by which something occurs through even more research/experimentation.
HOPE THIS HELPS
It is macular degeneration
Proteins are made of amino acids and they are components in most living things making up there structure.