Answer:
The correct answer is option A. Fish ladders
Explanation:
Fish ladders are a stair-like structure that gives the passage to the migrating fish to get around a dam to their destinations. As dams are an obstruction to fishes like salmon that migrate in the river upstream to breed, fish ladders have been created to allow the fish to get to their destinations by providing a passage around the dam.
Thus, the correct answer is option A. Fish ladder.