Capillarity is the phenomenon of a liquid rising or falling in a narrow tube due to the combination of cohesion and adhesion forces. The correct answer is option 'C' as both cohesion and adhesion forces are responsible for capillarity.

Cohesion:
Cohesion is the force of attraction between molecules of the same substance. In the case of a liquid, it is the force that holds the molecules of the liquid together. This is responsible for the surface tension of the liquid. The molecules at the surface of the liquid experience a net inward force due to the cohesive forces.

Adhesion:
Adhesion is the force of attraction between molecules of different substances. In the case of a liquid, it is the force that holds the molecules of the liquid to the surface of a solid. This is responsible for wetting of the surface by the liquid. The molecules at the interface between the liquid and the solid experience a net inward force due to the adhesive forces.

Capillarity:
When a narrow tube or capillary is dipped into a liquid, the liquid rises or falls in the tube due to the combination of cohesive and adhesive forces. The adhesive forces between the liquid and the walls of the capillary are responsible for the rise of the liquid in the tube. The cohesive forces between the molecules of the liquid are responsible for the curvature of the liquid surface near the walls of the capillary. The curvature of the liquid surface is inversely proportional to the radius of the capillary. The rise or fall of the liquid in the capillary is given by the formula:

h = (2Tcosθ)/ρgr

where h is the height of the liquid rise or fall, T is the surface tension of the liquid, θ is the contact angle between the liquid and the walls of the capillary, ρ is the density of the liquid, g is the acceleration due to gravity, and r is the radius of the capillary.

Conclusion:
In conclusion, capillarity is due to the combination of cohesive and adhesive forces. Cohesion is responsible for the surface tension of the liquid, while adhesion is responsible for wetting of the surface by the liquid. The rise or fall of the liquid in a capillary is given by a formula that considers the surface tension, contact angle, density of the liquid, acceleration due to gravity, and radius of the capillary.