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.

Example Input: What property is the same for each atom of an element?  
 (A) energy (B) mass number (C) atomic number (D) number of neutrons
Example Output: C

Example Input: A student wants to organize a group of animals into two categories based on observable external features. Which display will most appropriately show the two categories of animals?     
 (A) a timeline (B) a pie chart (C) a data table (D) a line graph
Example Output: C

Example Input: Which environmental stimulus causes leaves on certain trees to change color in autumn?  
 (A) loss of nutrients in the forest soil (B) lower air humidity in the forest (C) changes to amount of light (D) competition for survival
Example Output:
C