The correct option is D Ideal
When the solute A (liquid) dissolves in the solvent B (liquid), the extent of dissolution depends on interation of A-A, B-B and A-B.
Here, 100 mL of liquid 'A' and 25 mL of liquid 'B' mixed to form 125 mL. When these two liquids are added their volume became their sum of volume. There is no decrease or increase in volume after dissolution. This implies that the interaction of A and B is equal to the interaction of A-A and B-B.
For ideal solution, solvent-solute interaction is equal to solvent-solvent and solute-solute interactions.
ΔVmix=0 hence, the solution is ideal.