You are given a science question (hard-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 Q]: An atom becomes an ion with a -1 charge because the atom  
 (A) gains one electron. (B) loses one electron. (C) gains one proton. (D) loses one proton.
[EX A]: A

[EX Q]: A pharmaceutical company developed a drug to help relieve headaches. Recently, the pharmaceutical company discovered that the drug may cause nausea in a small number of people who might take the drug. Which is the most ethical course of action that the drug company could take?  
 (A) Discontinue the use of the drug. (B) Inform people of the possible side effects. (C) Reduce the amount of drug given to people. (D) Modify the drug to include medicine that prevents nausea.
[EX A]: B

[EX Q]: A group of students tested the effects of different amounts of water on ivy plant growth. Afterwards, they could not remember how much each plant grew per day. What should they have done to practice good science?  
 (A) Discuss their observations with other groups in their class. (B) Conduct the experiment with more than one type of plant. (C) Record daily information in a data table. (D) Make up explanations for the results.
[EX A]:
C