An ideal gas at $300\mathrm{K}$ is contained in a cylinder with a movable piston at $1.0\mathrm{atm}$. It is first heated at constant pressure until its volume doubles, then cooled at constant volume until the pressure halves. The final temperature is

1. A$300\mathrm{K}$
2. B$600\mathrm{K}$
3. C$150\mathrm{K}$
4. D$1200\mathrm{K}$