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 substance do all living things require to survive?  
 (A) blood (B) water (C) carbon dioxide (D) organic soil
[A]: B


[Q]: Which statement best describes the development of a human embryo?  
 (A) A single cell becomes many cells. (B) Each cell has a different function. (C) Many cells combine to form one cell. (D) All the cells have the same function.
[A]: A


[Q]: When bedrock in Massachusetts is examined, it often appears scraped and polished. Which of the following most likely caused the bedrock to appear scraped and polished?  
 (A) crustal deformation (B) frequent earthquakes (C) glacial movement (D) volcanic eruptions
[A]:
C