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

a. a decrease in the total biomass if producers in the world

b. an increase in the size of insects and arthropods

c. a decrease in total biomass of consumers in the world

d. all of these

im not 100% sure but i believe the answer is B. an increase in the size of insects and arthropods

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.