20 L of Gas a at 1 $\rarr$ C(g)
Assuming the Temperature Stays Constant, What Will Be the L

2.0 L of gas A at 1.0 atm and 1.0 L of gas B at 1.0 atm are combined in a 3.0 L flask. The flask is sealed and over time they react completely to give gas C according to the following chemical equation: 2A(g) + B(g) $\rarr$ C(g)
Assuming the temperature stays constant, what will be the pressure after the reaction goes to completion

A) 0.33 atm
B) 0.50 atm
C) 0.67 atm
D) 0.75 atm
E) 1.0 atm