What concept explains why the grains of cement prevent two surfaces from sliding?

Frictional resistance is the concept that explains why the grains of cement prevent two surfaces from sliding. When two surfaces come into contact, the microscopic roughness of those surfaces creates interlocking points and resistance to movement. This interaction generates friction, which acts as a counterforce to any applied force that would cause sliding. In the context of cement, the grains contribute to an increase in the surface area that comes in contact with each other, enhancing this resistance to sliding. The more uneven and interlocked the surfaces are, the greater the frictional force, making it difficult for the surfaces to move past one another. Thus, the presence of cement grains reinforces the stability of the joint and prevents motion through the mechanism of friction.

The other choices, such as convergence, kinematic tape, and elastic deformation, while relevant in different contexts, do not specifically address the fundamental mechanism of resistance to sliding that frictional resistance provides in this scenario.