Chemical Reactions Occur When Molecules,atoms,or Ions Collide

Chemical reactions occur when molecules,atoms,or ions collide.However,not every collision results in a reaction.In order for a reaction to occur,

A) the molecules must be big enough.
B) the energy of the molecules is not important,but the molecules must collide at the correct orientation.
C) the molecules must have enough kinetic energy and collide at the correct orientation.
D) the molecules must be moving slowly enough to interact,and must be rotating in opposite directions.