Final answer:
According to Charles's Law, the volume of a gas increases when the temperature is increased at a constant pressure.
Option C is correct.
Step-by-step explanation:
According to Charles's Law, when the temperature of a gas at constant pressure is increased, its volume increases. Charles's law explains that there is a direct relationship between the volume of a gas and its temperature when pressure is held constant. If the temperature rises, the kinetic energy of the gas particles also increases, which means the particles move faster and spread out more. To maintain constant pressure under these conditions, the volume of gas must increase, allowing the gas molecules to occupy a larger space and maintaining the rate of collisions with the container walls at a constant level.