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.

[Q]: 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.
[A]: B


[Q]: In which of these organs does most absorption of nutrients take place?  
 (A) liver (B) stomach (C) small intestine (D) large intestine
[A]: C


[Q]: The atmosphere of Mars is almost entirely composed of a greenhouse gas. Compared with Earth, which factor accounts for the low, nighttime surface temperatures on Mars?  
 (A) Mars is much farther from the Sun than Earth. (B) The atmosphere on Mars has an extremely low density. (C) The atmosphere on Mars lacks global circulation. (D) Mars has more glacial activity than Earth.
[A]:
B