Answer: Option A.
The type of relationship is Mutualism.
Explanation:
Mutualism is a type of symbiosis relationship that exist between organisms in which the two organisms benefits from the relationship. From the question above, the cleaner fish remove parasites from the big size fish. The big size fish benefits from the cleaner fish through protection from parasites attack and the big size fish keeps or protect cleaner fish from predators. The cleaner fish also benefit by receiving protection from predators. The two organisms benefits.