In the test tube shown, what is produced by the snail that is used by the plant?

In test tube C, both the water plant and the snail is kept. The plant further utilizes the carbon dioxide released by the snail for photosynthesis, and the snail utilizes by the plant for their respiration. Respiration is the process by which energy is released from food in our body.

some fungi obtain their nutrients from a living host (plant or animal) and are called most biotrophic fungi have fairly narrow host ranges—they are specialized on a limited called rhizomorphs that allow the fungus to grow from one tree to another. ascospores are formed inside a sac-like structure called an ascus. so your answer is a