A balloon filled with helium gas at 20 °C occupies 4.91 L at 1.00 atm (initial conditions). The balloon is then immersed in liquid nitrogen at -196 °C (77.15 K), while the pressure is raised to 5.20 atm. What is the volume of the balloon in the liquid nitrogen?
a. 97 L
b. 3.6 L
c. 0.25 L
d. 6.7 L