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 student plans to grow algal colonies in solutions with different concentrations of liquid fertilizer. Which is a clear and testable hypothesis to guide this investigation?  
 (A) Algae like fertilizer. (B) Fertilizer is good for algae. (C) Fertilizer improves the genetic traits of algae. (D) Algal growth rate increases with fertilizer concentration.

Ex Output:
D


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:
Which of these best describes a species?  
 (A) organisms that are similar in appearance (B) organisms that adapt to similar environments (C) organisms that can breed and produce fertile offspring (D) organisms that live together in the same area

Ex Output:

C