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 characteristic of sound makes it possible for bats to fly in the dark without hitting any objects?  
 (A) refraction (B) reflection (C) conduction (D) amplification

Ex Output:
B


Ex Input:
Which of these occurs if myosin fails to bind to actin during muscle contraction?  
 (A) The muscle cells will lose ATP. (B) The muscle cells will remain relaxed. (C) The muscle cells will produce lactic acid. (D) The muscle cells will lose calcium ions.

Ex Output:
B


Ex Input:
Which of the following is most likely to disrupt the natural balance in an ecosystem?  
 (A) introduction of a non-native species (B) reduced daylight hours during winter (C) preventing the cutting of trees in forests (D) riverbank erosion resulting from springtime flooding

Ex Output:

A