C. Mutualism I put the other answer and I got it wrong :(
Answer:
C.
mutualism
Explanation:
Microbial Mutualism with Orchids. Mycorrhizal fungi usually transfer nitrogen and phosphorus to plants, and receive carbohydrates. However, the orchid mycorrhizal symbiosis is unique because the mycorrhizal fungi transfer carbon to the plant, at least during early developmental stages.