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.

[EX Q]: Which set contains kingdoms that contain only heterotrophs?   
 (A) Protists, Fungi (B) Bacteria, Animals (C) Plants, Fungi (D) Animals, Fungi
[EX A]: D

[EX Q]: Which energy source is considered nonrenewable?  
 (A) moving water (B) fossil fuel (C) wind (D) biomass
[EX A]: B

[EX Q]: Why are most fossils found in sedimentary rocks?  
 (A) Sedimentary rocks are not very old. (B) Organisms live only in areas with sedimentary rock. (C) Organisms can be preserved in sedimentary rock. (D) Sedimentary rocks are found only at the surface of the ground.
[EX A]:
C