A thermally insulated vessel contains an ideal gas of molecular mass $M$ and ratio of specific heats $\gamma$. It is moving with speed $v$ and is suddenly brought to rest. Assuming no heat is lost to the surroundings, its temperature increases by:

1. A
   $\frac{(\gamma -1)M{v}^2}{2\gamma R}$
2. B
   $\frac{\gamma M{v}^2}{2R}$
3. C
   $\frac{(\gamma -1)M{v}^2}{2R}$
4. D
   $\frac{(\gamma -1)M{v}^2}{2(\gamma +1)R}$