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.

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

A: B
****
Q: A student pushed a large rubber ball on a flat, frictionless surface. The ball rolled at a speed of 1 meter per second. Which statement best describes the motion of the ball when the student stopped pushing the ball?  
 (A) The ball accelerated. (B) The ball did not move. (C) The ball changed direction. (D) The ball continued to move in the same direction.

A: D
****
Q: Sulfur (S), oxygen (O2), water (H2O), and sodium chloride (NaCl) are all examples of pure substances. Which of the following describes all pure substances?  
 (A) A pure substance consists of only one type of element. (B) A pure substance has a definite chemical composition. (C) A pure substance cannot be broken down into simpler substances. (D) A pure substance is normally found as a solid at room temperature.

A:
B
****