Answer:
The correct option is B) Freshwater snails and small fish
Step-by-step explanation:
As we can see from the food web, the fresh water snails and the small fishes both feed on algae and water plants as their source of food hence, both these organisms feed on the same food.
Other options, like option C, is not correct because water boatman and water plants do not feed on the same sources. Water boatman feeds on reeds whereas water plants do not. Water plants will make their own food.