Answer:
D. Bees benefit from drinking nectar from flowers, and the flowers are pollinated.
Step-by-step explanation:
Mutualism is when two different living things benefit from each other. When bees drink nectar from flowers, they are benefitting from that because they get nectar. The flowers are also benefitting from this because they are being pollinated.
A. is incorrect because the grass does not benefit
B. is incorrect because the dead animals are dead so they don't benefit from this
C. is incorrect because the fish are harmed and do not benefit from this
Therefore, the only correct answer is D.