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]: A geologist finds a layer of shale near the surface from a certain time period. Nearby, the geologist finds the same layer of shale, but it is deeper underground than the first layer. What might have caused the difference in the depth of the shale layer?  
 (A) a meteorite (B) a fault (C) ancient fossils (D) animal life
[EX A]: B

[EX Q]: A student pushes a box to slide it across the floor. Which statement explains why the box begins to move?  
 (A) The weight of the box is greater than the force of friction. (B) The weight of the box is less than the force of friction. (C) The applied force is greater than the force of friction. (D) The applied force is less than the force of friction.
[EX A]: C

[EX Q]: When coal burns, the reaction  
 (A) releases heat and is endothermic. (B) releases heat and is exothermic. (C) absorbs heat and is endothermic. (D) absorbs heat and is exothermic.
[EX A]:
B