A sample of helium gas had a volume of 900 milliliters and a pressure of 2.50 atm at 298 K. What's the new pressure when the temperature is changed to 336 K and the volume is decreased to 450 milliliters?
a) 1.25 atm
b) 2.50 atm
c) 3.75 atm
d) 5.00 atm