Which of the following could be caused by a decrease in carbon fixation?

An increase in the total biomass of consumers in the world

a decrease in the total biomass of consumers in the world

Explanation:

A decrease in carbon fixation would likely increase the amount of carbon dioxide in the air and decrease the amount of oxygen. This would change how much respiration and photosynthesis could take place, resulting in:

a decrease in the total biomass of consumers in the world,

an increase in the total biomass of producers in the world, and

a decrease in the size of insects and arthropods, since their ability to move oxygen from the air into and through their bodies is limited.

substitution is the answer in this case