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]: A student conducts an investigation. In order to make a valid conclusion, she must  
 (A) have a testable hypothesis. (B) place the data in a graph. (C) use the best technology. (D) test multiple variables.
[A]: A


[Q]: A student is investigating which type of soil is best for growing tomato plants from seeds. The student plants four tomato seeds in each of three different containers of soil. Which step of the procedure would help the student get the most reliable results?  
 (A) Place one container in a dark room. (B) Use different types of tomato seeds. (C) Change only the soil type in each container. (D) Water each container with a different amount of water.
[A]: C


[Q]: Between the ages of 8 and 13, young boys' and girls' bodies begin to change. This is the beginning point of children becoming adults. During these years, the endocrine system releases certain types of hormones. What is most likely being regulated by this system?  
 (A) absorption of water and nutrients (B) growth and development of the body (C) blood flow to the cells and major organs (D) rate that waste is eliminated from the body
[A]:
B