SAT OwlCleaner wrasses are small fish that eat parasites off the skin of larger "client" fish. The cleaners, however, would rather eat the protective mucus that coats their clients' skin, and they sometimes take a bite of it, which makes the client jolt and often swim away. Marine biologist Ana Esteves observed that when other client fish were waiting nearby and could see the cleaning, cleaners bit their current client far less often. This behavior suggests that cleaners ______
Which choice most logically completes the text?
behave more cooperatively when doing so may help them win future clients.
come to prefer eating parasites over eating mucus when other fish are present.
can tell which clients are carrying parasites and which are not.
bite clients mainly to drive away competing cleaner fish.
Show answer and explanation
Answer: A
Bites make clients swim away, and cleaners bite less when other clients are watching. The likeliest explanation is that cleaners hold back to keep a good reputation with the fish that are waiting, choice A.
Choice B confuses behavior with preference. The text says cleaners would rather eat mucus; being watched changes what they do, not what they want.
Why the other choices are wrong
- B. The text says cleaners would rather eat mucus. Being watched changes their behavior, not their preference.
- C. Nothing in the text concerns whether clients carry parasites, so this ability has no support.
- D. The text never mentions competing cleaners. Bites happen because cleaners like eating mucus.
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