A) Collision doesn't require physical contactB) Collision between sub atomic particles is elasticC) Collision between macroscopic bodies is generally inelastic.

When two charged particles, carrying like charge, collide, actual contact does not take place. In this case after a minimum separation, the distance between the particles starts increasing because of the action of repulsive electro static force. In this case there is no question of deformation of the particles so the collision is elastic. In case of collision between macroscopic particles, actual physical contact takes place and the particles are deformed at the point of contact. In case of inelastic collision, the particles cannot completely regain their original shape and size.