$A$ container is divided into two compartments by a removable partition as shown below:
In the first compartment,$n_{1}$ moles of ideal gas $He$ is present in a volume $V_{1}$. In the second compartment,$n_{2}$ moles of ideal gas $Ne$ is present in a volume $V_{2}$. The temperature and pressure in both the compartments are $T$ and $p$,respectively. Assuming $R$ is the gas constant,the total change in entropy upon removing the partition when the gases mix irreversibly is:

• A
  $n_{1} R \ln \frac{V_{1}}{V_{1}+V_{2}} + n_{2} R \ln \frac{V_{2}}{V_{1}+V_{2}}$
• B
  $n_{1} R \ln \frac{V_{1}+V_{2}}{V_{1}} + n_{2} R \ln \frac{V_{1}+V_{2}}{V_{2}}$
• C
  $(n_{1}+n_{2}) R \ln \frac{n_{1} V_{1}}{n_{2} V_{2}}$
• D
  $(n_{1}+n_{2}) R \ln \frac{n_{2} V_{2}}{n_{1} V_{1}}$