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 Input:
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 Output:
B


Ex Input:
Which situation is the best example of an inherited trait?  
 (A) a boy playing with a ball (B) a bird building a nest (C) a horse pulling a wagon (D) a dog sitting on command

Ex Output:
B


Ex Input:
Which is an example of primary ecological succession?  
 (A) plants and animals invading an abandoned crop field (B) mangroves stabilizing the soils on tropical coasts (C) minerals spurring rapid plant growth (D) lichen growth on rocks

Ex Output:

D