Charles's Law states that the volume of a gas is directly proportional to its absolute temperature (in Kelvin) when pressure is held constant. This relationship is expressed mathematically as V1/T1 = V2/T2, where V represents volume and T represents absolute temperature. Option A incorrectly inverts the ratio, option B is the Ideal Gas Law (not Charles's Law), and option D incorrectly swaps the temperature and volume subscripts.