A) cellular respiration, erosion, and combustion.

B) assimilation, photosynthesis, and respiration
C) decomposition, erosion, and assimilation
D) combustion, photosynthesis, and decomposition.

Hello! I'm debating between A and D, but I'm leaning a lot towards A
What do you think?

What's the question?? !!

Since Jiskha doesn't have a biology expert at this time, please try posting your question at this site.

http://www.biology-online.org/biology-forum/

In addition, be sure to make really good use of Khan Academy!
http://www.khanacademy.org/science/biology
Choose from the general topics at the right and then find the specifics you need within each topic.

Both options A and D contain three processes related to energy and matter exchange in different ways, but they are actually quite different in terms of their specific processes. It's important to understand each process to make an informed decision.

Option A includes cellular respiration, erosion, and combustion. Cellular respiration is the process by which living organisms convert organic molecules into energy in the form of ATP (adenosine triphosphate). Erosion, on the other hand, refers to the processes of weathering, transport, and deposition of soil, sediment, and rocks by wind, water, and ice. Combustion, the last process in option A, involves the reaction of a substance with oxygen to release energy in the form of heat and light.

Option D, on the other hand, includes combustion, photosynthesis, and decomposition. Combustion, as explained before, is the reaction of a substance with oxygen to release energy. Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose. Decomposition, the last process in option D, involves the breakdown of dead organic matter by bacteria and fungi into simpler compounds.

Considering these explanations, it seems that option D (combustion, photosynthesis, and decomposition) is a more accurate representation of processes related to energy and matter exchange.