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 would provide evidence of seafloor spreading?  
 (A) higher levels of salinity in the ocean water (B) stronger currents at the surface of the ocean (C) cooled magma found on the edge of the plates (D) greater reproduction levels for organisms at the bottom of the ocean

Ex Output:
C


Ex Input:
Which provides the oldest evidence for oxygen accumulation in Earth's atmosphere?  
 (A) the earliest fossils of animals (B) the earliest sediments of oxidized rock (C) impact craters of oxidized-iron asteroids (D) extensive volcanic calderas of similar age

Ex Output:

B