A thermo-dynamical system is changed from state $({\mathrm{P}}_1,{\mathrm{V}}_1)$ to $({\mathrm{P}}_2,{\mathrm{V}}_2)$ by two different process. The quantity which will remain same will be 

• A

  $\mathrm{\Delta }\mathrm{Q}$

• B

  $\mathrm{\Delta }\mathrm{W}$

• C

  $\mathrm{\Delta Q}+\mathrm{\Delta W}$

• D

  $\mathrm{\Delta Q}-\mathrm{\Delta W}$