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:
Which of these is a renewable resource found in Nevada?  
 (A) zinc metal (B) gravel deposits (C) petroleum products (D) geothermal energy

Ex Output:
D


Ex Input:
What gas in the air do we need to breathe in order to live?  
 (A) nitrogen (B) oxygen (C) carbon dioxide (D) hydrogen (E) water vapor

Ex Output:
B


Ex Input:
Which steps in the water cycle most directly cause floods?  
 (A) precipitation and runoff (B) condensation and evaporation (C) runoff and condensation (D) evaporation and precipitation

Ex Output:

A