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:
What determines how long the Moon takes to complete one cycle of phases?  
 (A) the period of rotation of the Moon around its axis (B) the period of revolution of the Moon around Earth (C) the period of rotation of Earth around its axis (D) the period of revolution of Earth around the Sun

Ex Output:
B


Ex Input:
Spring tides occur during which lunar phases?  
 (A) first quarter and last quarter (B) full moon and new moon (C) when the moon is waxing (D) when the moon is waning

Ex Output:
B


Ex Input:
A student is working on a science project display for the school science fair. To best communicate why her conclusions are valid, what should be included on the display?  
 (A) a list of authoritative sources that supports her conclusion (B) instructions for viewers to repeat her procedures (C) clearly illustrated diagrams of the scientific principles involved (D) a complete write-up of her experimental method and data collected

Ex Output:

D