Answer: D: 800 K to 200 K.
Step-by-step explanation:
The pressure of a gas is directly proportional to its temperature on the Kelvin scale. This means that if the temperature of a gas increases, the pressure of the gas will also increase, and if the temperature decreases, the pressure will also decrease.
If the pressure of a gas in a rigid container is halved when the temperature changes, this means that the temperature must have decreased by a factor of 2.
Looking at the options provided, the only temperature change that could be responsible for halving the pressure is:
D. 800 K to 200 K
The temperature decreased by a factor of 4 (800 K / 200 K = 4), which is more than the factor of 2 needed to halve the pressure.