An example of a liquid-liquid mixture is
Oil in water
Mixtures
Liquid-Liquid mixtures: These are those types of mixtures in which both solute and solvent are liquid.
The explanation for the correct answer:
(A) - Oil in water
The explanation for the incorrect answers:
(B) - Muddy water
(C) -Smoke
(D) -Steel
Therefore option (D) is the correct answer.