At point A, the beam undergoes tensile strain, therefore hole at A will increase in size along the length of the beam and becomes oblate.
At point C, the beam undergoes compression strain, therefore hole at C will decrease in size along the length of beam and becomes prolate.
The point B is in neutral zone, therefore the hole at B will be circular.
Inter-atomic or inter-molecular forces are electrostatic in nature.
Adhesive force is the attractive force between two unlike molecules. They are caused by forces acting between two substances like electrostatic force (attraction due to opposing charges), mechanical force etc.
E.g., Force of attraction between gum and paper.