Task: Question Generation
Input (English): Background Paragraph: Shown in the Figure below is a cylinder of gas on the left that is at room temperature (300 K). On the right, the cylinder has been heated until the Kelvin temperature has doubled to 600 K. The kinetic energy of the gas molecules increases, so collisions with the walls of the container are now more forceful than they were before. As a result, the pressure of the gas doubles. Decreasing the temperature would have the opposite effect, and the pressure of an enclosed gas would decrease. 
Story: Rob is testing the properties of gas. To that end, he experimented with a cylinder of gas in three stages, stage A, stage B, and stage C. In stage A he kept the gas in room temperature. In stage B he heated the gas up. And in stage C he cooled the gas down.
Output (English): Which stage would see decreased pressure, stage B or stage C?