TASK DEFINITION: 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.
PROBLEM: 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.

SOLUTION: A

PROBLEM: Which of these animals has a young form that looks the most like the adult form?  
 (A) moth (B) human (C) frog (D) butterfly

SOLUTION: B

PROBLEM: What characteristic of viruses distinguishes them from cells?  
 (A) They do not have hereditary material. (B) They are not separated from their environments. (C) They lack an independent metabolism. (D) Their traits do not evolve in response to selection pressures.

SOLUTION:
C