Answer
A
Work Step by Step
Van der Waals equation:
$\left[P+a\left(\dfrac nV\right)^2\right](V-bn)=nRT$
$n=343\ mol, V=473\ L, T=(25+273)=298\ K, R=0.082057\ L.atm/mol.K$
$a=0.034\ atm.L^2/mol^2, b=0.0237\ L/mol$
$P=11202\ L.atm/462\ L-0.0179\ atm$
$P=18.0\ atm$