You must follow the Gay-Lussac law of gases but, and this is extremely important, using temperature in Kelvin scale:
[tex]\frac{P_1}{T_1} = \frac{P_2}{T_2}\ \to\ P_2 = \frac{P_1\cdot T_2}{T_1} = \frac{13\ atm\cdot (102 + 273)\ K}{(20 + 273)\ K} = \bf 16.64\ atm[/tex]
The correct answer is C) 16.6 atm.
