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 Q]: Which of these is an inherited behavior?  
 (A) a seal balancing a ball (B) a dog getting the newspaper (C) a spider spinning a web (D) an ape using sign language
[EX A]: C

[EX Q]: When do mutations help make an ecosystem more sustainable?  
 (A) when mutations decrease the number of individuals in an ecosystem (B) when mutations increase the number of individuals in an ecosystem (C) when mutations decrease the number of species in an ecosystem (D) when mutations increase the number of species in an ecosystem
[EX A]: D

[EX Q]: Tooth decay is an infection that causes deterioration of the protective enamel on teeth, resulting in damage. Tooth decay is most likely caused by  
 (A) bacteria. (B) acidic food. (C) allergies. (D) genetic defects.
[EX A]:
A