If liquid is dispersed in solid medium, then it is known as
(A) Sol
(B) Emulsion
(C) Liquid Aerosol
(D) Gel

Hint:
Colloids are a primary type of mixture that have particles of size between $1$ to $1000$ nanometer (nm). The mixture has two components: the dispersed phase and dispersion medium which can be a solid liquid or a gas.

Complete step by step answer:
The collides are of eight different types based on their dispersion medium and dispersed phase The table below shows the common example of colloids.

DISPERSED PHASE	DISPERSED MEDIUM	TYPE	EXAMPLE
Liquid	Liquid	Emulsion	Face cream
Gas	Liquid	Foam	Shaving cream
Solid	Liquid	Sol	Mud
Liquid	Solid	Gel	Cheese
Gas	Solid	Foam	Sponge
Solid	Solid	Solid sol	Gemstones
Solid	Gas	Aerosol	Smoke
Liquid	Gas	Aerosol	fog

-As we can see in the table if a liquid is dispersed in a solid phase that means liquid is dispersed phase and solid is dispersing medium then the colloid is known as gel. Examples of this gel are cheese, butter etc.
-The gels are semisolid and can be either soft and wear or strong and hard. The gels appear solid due to three- dimensional cross linked structure.
-In ${19^{th}}$ century, Thomas Graham, a Scottish chemist gave the term gels.
Hence option D is correct.

Additional information:-
-Gels show thixotropy, that means, when the gel is shaken it turns into fluid but then resolidify while resting
-Gels are formed when a gelling agent is added and by this approach many products like foods paints adhesives etc. can be manufactured.
-These gels even exist inside humans as vitreous humor in the eye, cartilages, tendons, blood clots, mucus etc.

Note:It should be remembered that gel only formed when the dispersed phase is a liquid and dispersion medium is a solid. If we do the inverse and take a solid as a dispersed phase and a liquid as a dispersion medium it will lead to formation of sols. Eg Mud
-The gels maintain their three dimensional cross linked structure with the help of bonding between different particles.