Task: Question Generation
Input (English): Background Paragraph: Start right above point on the temperature axis and follow the red line vertically. At very low pressure, the particles of the substance are far apart from one another and the substance is in the gas state. As the pressure is increased, the particles of the substance are forced closer and closer together. Eventually the particles are pushed so close together that attractive forces cause the substance to condense into the liquid state. Continually increasing the pressure on the liquid will eventually cause the substance to solidify. For the majority of substances, the solid state is denser than the liquid state and so putting a liquid under great pressure will cause it to turn into a solid. The line segment represents the process of sublimation, where the substance changes directly from a solid to a gas. At a sufficiently low pressure, the liquid phase does not exist. The point labeled is called the triple point . The triple point is the one condition of temperature and pressure where the solid, liquid, and vapor states of a substance can all coexist at equilibrium. 
Story: Dan is conducting a research to see how a substance behaves in varying pressure. First, he selects a gaseous substance in very low pressure. He calls it as case A. Then he increases the pressure. He calls it case B. Finally, he increases the pressure even further. He calls it case C.
Output (English): Which case would see less distance between particles, case B or case C?