Three containers of the same volume contain three different gases. The masses of the molecules are \[{{m}_{1}},{{m}_{2}}\]and \[{{m}_{3}}\]the number of\[{{N}_{1}}\], \[{{N}_{2}}\] and \[{{N}_{3}}.\] The gas pressure in the containers \[{{P}_{1}},{{P}_{2}}\] and \[{{P}_{3}}\] respectively. All the gases are now mixed and put in one of these containers. The pressure P of the mixture will be

• A. \[P<\left( {{P}_{1}}+{{P}_{2}}+{{P}_{3}} \right)\]     
• B. \[P=\frac{{{P}_{1}}+{{P}_{2}}+{{P}_{3}}}{3}\]
• C. \[P={{P}_{1}}+{{P}_{2}}+{{P}_{3}}\]         
• D. \[P>\left( {{P}_{1}}+{{P}_{2}}+{{P}_{3}} \right)\]