A. The ecosystem can support fewer foxes than grasshoppers.
Explanation:
Since the energy has to transfer from organism to organism, it reduces in amount. Since there are more grasshoppers than foxes, than the ecosystem can support grasshoppers easily.
Photosynthesis requires sunlight for plants to make food. Therefore, the rate of photosynthesis in December would be slower than in July, since there is less sun in December :)