You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.

What is a decomposer?  
 (A) a living thing that breaks down dead organisms (B) a living thing that makes its own food (C) an animal that eats live plants (D) an animal that hunts other animals
A

A scanning electron microscope is best suited for observing  
 (A) diffraction of light. (B) tectonic features on planets. (C) the surfaces of small objects. (D) topographical features on the ocean floor.
C

A scientist was investigating why several fish caught from a local stream displayed similar mutations. He found that the water temperature of the stream was elevated since an industrial plant began discharging heated water into the stream. The scientist concluded that increased water temperature during the egg phase led to the mutation in the fish. According to this conclusion, the mutation was caused by  
 (A) an autoimmune disorder. (B) a congenital defect. (C) an environmental condition. (D) an injury from a predator.

C