The correct option is A It is due to bond formation between the surfaces.
The surface of glass is smooth and even. So, interlocking of surface irregularities does not play any major role in friction. Also, the surfaces, being hard, cannot get deformed easily. The reason for the high level of friction between these two surfaces is because of the formation of bonds. As a result of this, these surfaces acquire a property called adhesion or stickiness. It takes effort to break these bonds and hence there is a high friction between the surfaces.