Answer
A
Work Step by Step
Since $n=PV/RT$ and T and P are equal: $n\propto V$
Since the ratio of the volumes : $4.0\ L/1.5\ L=2.67\lt 3$
Oxygen is the limiting reactant.
Number of moles of oxygen:
$n=4.0\ LĂ1\ atm/0.082057\ L.atm/mol.K/273\ K$
$n=0.179\ mol$
From stoichiometry, that's the same as the number of moles of water.