A body of density \[{{d}_{1}}\]is counterpoised by \[Mg\] of weights of density \[{{d}_{2}}\] in air of density d. Then the true mass of the body is

• A.            M  
• B.            \[M\,\left( 1-\frac{d}{{{d}_{2}}} \right)\]                    
• C.            \[M\left( 1-\frac{d}{{{d}_{1}}} \right)\]                        
• D.            \[\frac{M(1-d/{{d}_{2}})}{(1-d/{{d}_{1}})}\]