The correct answer is A. why a balloon deflates when the air around it cools
Explanation:
According to Charles' law, in gases the temperature and volume are related, in this way the volume of a gas increases if these are heated or if the temperature rises and in the same way the volume of a gas decreases as the temperature falls. This law explains "why a balloon deflates when the air around it cools" because this shows the gas in the balloon reduces its volume and therefore deflates when the temperature decreases, which shows the relationship between temperature and volume described in Charles' law.
