Step 1: Understanding the analogy.
Flow is a characteristic of a river, meaning a river typically has a flow. We need to find a similar relationship for stagnant.
Step 2: Analyzing the options.
(A) Rain: Rain is not directly related to stagnation, so this option doesn’t fit.
(B) Stream: A stream has flow, making it the opposite of stagnant.
(C) Pool: Correct — A pool is typically stagnant, just like how a river is flowing.
(D) Canal: A canal often has flow and is not stagnant.
Step 3: Conclusion.
The correct answer is (C) Pool, as a pool can be stagnant, like how a river typically has flow.