Statement (A): Molarity always equals to its molality.

Statement (B): The amount of solvent in 1M aqueous solution is more than in 1m aqueous solution

Statement (C): At $25°\text{C}$, for a given solution M- m, then at $50°\text{C}$ the correct relation is $\text{M}<\text{m}$.

Statement I, Molarity is always equal to its molality is wrong because in molality the amount of solvent to be fixed (1kg) but in molarity the weight of solvent is less than 1kg.

Statement II, the amount of solvent in 1 M aqueous solution is less than in 1m aqueous solution. So it is wrong .

In statement III,at high temperature, M < m. This is true because increase in temperature increases the volume (as per Charles’s law). As volume of solution increases then molarity decreases.