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 two body systems maintain the level of glucose in the blood?  
 (A) nervous and respiratory systems (B) digestive and endocrine systems (C) muscular and immune systems (D) skeletal and cardiac systems
[EX A]: B

[EX Q]: A light year is used to measure  
 (A) time. (B) distance. (C) luminosity. (D) temperature.
[EX A]: B

[EX Q]: Some animals, such as squirrels, may bury acorns. Which of the following is most likely to happen to the acorns after they have been buried?  
 (A) The acorns will be carried away by the wind. (B) The acorns will attach to another organism. (C) The acorns will have a chance to sprout. (D) The acorns will turn into fossils.
[EX A]:
C