The correct option is
In air, various gases are mixed together uniformly. Nitrogen can be considered as the solvent here as it is present in the largest amount.
CO2 dissolved in water is an example of a gas solute in a liquid solvent.
Sugar dissolved in water is an example of a solid dissolved in a liquid.
Alloys are homogenous mixtures of two or more metals/ non metals and are classic examples of solid-solid solutions. For example, in stainless steel, iron can be considered as the solvent as it is present in the largest quantity, whereas carbon, chromium, nickel etc can be considered as solutes.