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.

A student notices that an inflated balloon gets larger when it is warmed by a lamp. Which best describes the mass of the balloon as a result of this change?  
 (A) The mass of the balloon increases because the size of the balloon has increased. (B) The mass of the balloon increases because the temperature of the balloon has increased. (C) The mass of the balloon stays the same because the gas inside the balloon still has the same mass after it warms up. (D) The mass of the balloon stays the same because warming decreases the mass enough to cancel out the effect of increasing the size.
C

What is one way to change water from a liquid to a solid?  
 (A) decrease the temperature (B) increase the temperature (C) decrease the mass (D) increase the mass
A

Light waves travel faster than sound waves, so a lightning bolt can be seen before the thunder is heard. Which factor can also affect how quickly thunder is heard?  
 (A) the electrical charge of the sound waves (B) the direction in which the sound waves travel (C) the amount of energy released by each sound wave (D) the type of material through which the sound travels

D

