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:
Historically, how has the compass been used?  
 (A) for navigation (B) to predict weather (C) to measure temperature (D) for mineral identification

Ex Output:
A


Ex Input:
Which particle type can be identified as being from a specific element?  
 (A) electron (B) atom (C) neutron (D) proton

Ex Output:
B


Ex Input:
A group of students is taking a hike along a stream channel. One student picks up a rock from the stream and notices that the rock is very smooth and round. Which type of weathering most likely shaped the rock?  
 (A) abrasion (B) exfoliation (C) fracturing (D) oxidation

Ex Output:

A