Task: Question Answering
Input (English): Background Paragraph: Pressures are given in a multitude of units. We've already discussed Pascals, and we know that another unit for pressure is the atmosphere (1 atm = 101.3 x 10 5 Pa). The third commonly used pressure unit is the torr (symbol Torr). 760 torr is 1 atm, but 1 torr is also the increase in pressure necessary to cause liquid mercury to rise by 1 mm. For that reason, torr is also commonly referred to as "millimeters mercury." Another pressure unit commonly used in our everyday world is psi, or pounds per square inch, though neither psi nor torr are SI units. 
Story: Mike is studying for his physics exam. He realizes that the best way to learn physics is to solve problems. To that end, he needs to to convert pressure of objects from one unit to another. In one problem, four scenarios are given for the same object, scenario A, scenario B, scenario C, and scenario D. In scenario A the pressure is given in Pascals. In scenario B the pressure is given in the atm. In scenario C the pressure is given in torr. Lastly, in scenario D the pressure is given in psi. 
Question: In which scenario mercury may not be a factor in devising the unit, scenario A or scenario C?
Output (English): scenario A.