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]: Planets in the solar system are in constant motion. What factor has the greatest effect on the orbits of the planets?  
 (A) the size of the planets (B) gravitational pull of the Sun (C) the composition of the planets (D) electromagnetic radiation from the Sun
[EX A]: B

[EX Q]: Scientists wonder how the Egyptian pyramids were built. They think that the huge blocks of stone may have been put into place by pushing them up a sloping pathway. The pathway is which type of simple machine?  
 (A) lever (B) pulley (C) inclined plane (D) wheel and axle
[EX A]: C

[EX Q]: A group of scientists is studying the effect of cell phone signals on honeybees. Before starting the investigation, the scientists stated that the bees exposed to cell phone signals will have difficulty finding their way back to the hive. Which term best describes the statement made by the group of scientists?  
 (A) control (B) data (C) hypothesis (D) variable
[EX A]:
C