Three liquids of equal volumes are thoroughly mixed. If their specific heats are \[{{\operatorname{s}}_{1}},\,\,{{s}_{2}},\,\,{{s}_{3}}\] and their temperatures \[{{\theta }_{1}},{{\theta }_{2}},{{\theta }_{3}}\] and their masses \[{{\operatorname{m}}_{1}},\,\,{{m}_{2}},\,\,{{m}_{3}}\] respectively, then the final temperature of the mixture is

• A. \[\frac{{{s}_{1}}{{\theta }_{1}}+{{s}_{2}}{{\theta }_{2}}+{{s}_{3}}{{\theta }_{3}}}{{{m}_{1}}{{s}_{1}},\,\,{{m}_{2}}{{s}_{2}},\,\,{{m}_{3}}{{s}_{3}}}\]
• B. \[\frac{{{m}_{1}}{{s}_{1}}{{\theta }_{1}}+{{m}_{2}}{{s}_{2}}{{\theta }_{2}}+{{m}_{3}}{{s}_{3}}{{\theta }_{3}}}{{{m}_{1}}{{s}_{1}},\,\,{{m}_{2}}{{s}_{2}},\,\,{{m}_{3}}{{s}_{3}}}\]
• C. \[\frac{{{m}_{1}}{{s}_{1}}{{\theta }_{1}}+{{m}_{2}}{{s}_{2}}{{\theta }_{2}}+{{m}_{3}}{{s}_{3}}{{\theta }_{3}}}{{{m}_{1}}{{\theta }_{1}},\,\,{{m}_{2}}{{\theta }_{2}},\,\,{{m}_{3}}{{\theta }_{3}}}\]
• D. \[\frac{{{m}_{1}}{{\theta }_{1}}+{{m}_{2}}{{\theta }_{2}}+{{m}_{3}}{{\theta }_{3}}}{{{\operatorname{s}}_{1}}{{\theta }_{1}},\,\,{{\operatorname{s}}_{2}}{{\theta }_{2}},\,\,{{\operatorname{s}}_{3}}{{\theta }_{3}}}\]