Instructor is never required to drop you from your math course.
Answer: B
Explanation:
"Furthermore, ectomycorrhizal fungi can slow down decomposition, a natural process that returns carbon from forest soils back to the atmosphere. In these ways, ectomycorrhizal fungi enhance the ability of forests to keep carbon locked up in trees and soils, and out of the atmosphere." (http://www.bu.edu/articles/2018/4-things-to-know-about-fungi-climate-warriors/)
Gas exchange is the delivery of oxygen from the lungs to the blood stream, and gets rid of carbon dioxide from the blood. It occurs in the lungs between the alveoli and a group of capillaries.