ANS:C - 0°R

Absolute zero pressure can be attained at a temperature of 0 Kelvin (0 K). Absolute zero is the lowest possible temperature at which the entropy of a perfect crystal is exactly zero. At this temperature, the fundamental particles of matter have minimal vibrational motion, and all thermal activity ceases. According to the ideal gas law, pressure is directly proportional to temperature when volume and the number of particles are held constant. Therefore, at absolute zero temperature, the pressure of a gas approaches zero. In the Kelvin temperature scale, absolute zero is defined as 0 K, making it the appropriate temperature unit for discussing phenomena at absolute zero pressure. While 0°C and 0°R (Rankine) represent absolute zero in the Celsius and Rankine temperature scales, respectively, they do not correspond to the absence of pressure.