In styrene foam, the dispersed phase and dispersion medium respectively are:
A.Gas, gas
B.Gas, solid
C.Solid, solid
D.Liquid, solid

Hint: Dispersed phase: The phase in which the colloidal particles exist, are known as dispersed phases.
Dispersion medium: The medium in which the colloidal particles are distributed, is known as dispersion medium.

Complete step by step answer:
First of all we will talk about colloidal particles, dispersed and dispersion mediums.
Colloidal mixtures: It is defined as the mixture in which the tiny particles are suspended throughout another substance.
Dispersion phase: The phase in which the colloidal particles exist, are known as dispersed phases.
Dispersion medium: The medium in which the colloidal particles are distributed, is known as dispersion medium.
Colloid mixtures are of many types based on the size of dispersed phase:
Multi-molecular colloids: The solutions which are formed due to large numbers of atoms or small molecules, are known as multi-molecular colloids. For example: Gold sol, sulphur sol.
Macromolecular colloids: The solutions which form heavy molecules, are known as macromolecular colloids. For example: starch, proteins.
Associated colloids: Those solutions which behave as strong electrolytes at lower concentration but show colloidal properties at higher concentration, are known as associated colloids. For example: micelles.
Colloid mixtures are of many types based on dispersed phase and dispersion medium:
If the dispersed phase is liquid and dispersion medium is gas then the colloidal solution is known as liquid aerosol. For example: mist, clouds and foam.
If the dispersed phase is solid and the dispersion medium is gas then the colloidal solution is known as aerosol. For example: dust and smoke.
If the dispersed phase is gas and dispersion medium is liquid then the colloidal solution is known as foam. For example: whipped cream.
If the dispersed phase is liquid and the dispersion medium is liquid then the colloidal solution is known as emulsion. For example: cream, milk.
If the dispersed phase is solid and the dispersion medium is liquid then the colloidal solution is known as sols. For example: paints, jellies.
If the dispersed phase is gas and the dispersion medium is solid then the colloidal solution is known as solid foam. For example: marshmallow.
If the dispersed phase is liquid and the dispersion medium is solid then the colloidal solution is known as solid emulsion. For example: butter, cheese.
If the dispersed phase is solid and the dispersion medium is solid then the colloidal solution is known as solid sol. For example: alloys.

So, the correct answer is Option B .

Note:
Alloys: It is defined as the metallic compounds made of one metal with another metal or one metal with another substance. For example: steel is an alloy iron which is metal and carbon which is non-metal.