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.
--------
Question: 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.

Answer: A


Question: Use of nuclear fuel would most likely reduce human contributions to which environmental problem?  
 (A) ozone thinning (B) landfill creation (C) shoreline erosion (D) greenhouse heating

Answer: D


Question: Astronauts weigh more on Earth than they do on the moon because  
 (A) they have less mass on the moon. (B) their density decreases on the moon. (C) the moon has less gravity than Earth. (D) the moon has less friction than Earth.

Answer:
C