Please Help me (I'll give brainlest) (LIMITED)

Answer:
C is correct I think
Explanation:
A: Couldn't be because there is one less source that is consuming the algae, so algae wouldn't decrease
B: Number of pike wouldn't increase because it would be getting less food
C is correct because there would be less pike because there would be less food for them, so fishermen would catch less
D: Same explanation as B but for Dragonfly larvae