A 5.25% solution of a substance is isotonic with a 1.5% solution of urea (molar mass = $60 \; g\; mol^{-1}$) in the same solvent. If the densities of both the solutions are assumed to be equal to $1.0\; g\; cm^{-3}$, molar mass of the substance will be :

Question

( A ) $210.0\;g\;mol^{-1}$
( B ) $90.0\;g\;mol^{-1}$
( C ) $115.0\;g\;mol^{-1}$
( D ) $105.0\;g\;mol^{-1}$