A vertical cylinder closed at the bottom is fitted with a frictionless piston of negligible mass and traps an ideal gas of column height $h$ at atmospheric pressure $P_0$. A weight is placed on the piston so that the pressure exerted by the weight alone equals $P_0/3$. At constant temperature, the new height of the gas column is

1. A$\frac{3h}{4}$
2. B$\frac{h}{3}$
3. C$\frac{2h}{3}$
4. D$\frac{4h}{3}$