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.

Which of these do all cells release?  
 (A) sugar (B) water (C) energy (D) oxygen
C

A thermometer is best used to measure  
 (A) air pressure. (B) kinetic energy. (C) potential energy. (D) wind movement.
B

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.

A