Among the colloids cheese (C), milk (M) and smoke (S), the correct combination of the dispersed phase and dispersion medium, respectively is:

First, let us recall the basic definition of a colloid. In a colloidal system we always have two distinct components:

$$\text{Colloid} = \text{Dispersed phase} + \text{Dispersion medium}$$

The dispersed phase (also called the discontinuous phase) is the substance present as tiny particles, while the dispersion medium (also called the continuous phase) is the substance in which those tiny particles are scattered. The nature (solid, liquid or gas) of each of these two components allows us to place any colloid into a named class such as sol, gel, foam, aerosol, etc.

Now we identify the dispersed phase and the dispersion medium for each material mentioned in the question.

Cheese (C)

• Cheese is obtained by coagulating milk proteins. A protein-water mixture first converts into a semi-solid mass in which water is trapped within a continuous three-dimensional network formed by protein molecules and fat droplets.
• That continuous network behaves like a solid skeleton, while the trapped liquid (mostly water with dissolved substances) is the dispersed phase.
• Therefore, for cheese we have:

$$\text{Dispersed phase} = \text{liquid}, \qquad \text{Dispersion medium} = \text{solid}$$

This type of colloid is technically called a gel.

Milk (M)

• Milk consists of tiny droplets of fat and casein protein micelles scattered throughout water.
• Here water itself is in much larger proportion and forms a continuous phase, whereas the fat/protein droplets are the discontinuous phase.
• Consequently, in milk we have:

$$\text{Dispersed phase} = \text{liquid}, \qquad \text{Dispersion medium} = \text{liquid}$$

Such a colloid (liquid in liquid) is called an emulsion.

Smoke (S)

• Smoke is produced by incomplete combustion, giving fine carbon or ash particles floating in air.
• Those carbon/ash particles are solid, while the surrounding continuous phase (air) is gaseous.
• Hence, for smoke we write:

$$\text{Dispersed phase} = \text{solid}, \qquad \text{Dispersion medium} = \text{gas}$$

This category is termed a solid aerosol.

Let us summarise all three systems together:

$$ \begin{aligned} \text{Cheese}: &\; \text{liquid in solid} \\ \text{Milk}: &\; \text{liquid in liquid} \\ \text{Smoke}: &\; \text{solid in gas} \end{aligned} $$

Now we compare this result with the four options supplied:

Option A: C : liquid in solid; M : liquid in solid; S : solid in gas    → Milk part incorrect.
Option B: C : liquid in solid; M : liquid in liquid; S : solid in gas    → All three correct.
Option C: C : solid in liquid; M : liquid in liquid; S : gas in solid    → Cheese and smoke both incorrect.
Option D: C : solid in liquid; M : solid in liquid; S : solid in gas    → Cheese and milk incorrect.

Only Option B matches every description perfectly.

Hence, the correct answer is Option B.