I believe the correct answer is a. mutations.
Selective logging—the practice of removing one or two trees and leaving the rest intact—is often considered a sustainable alternative to clear-cutting, in which a large swath of forest is cut down, leaving little behind except wood debris and a denuded landscape.
A) single loop
Fish have a two-chambered heart in which a single-loop circulatory pattern takes blood from the heart to the gills and then to the body.
