What is the definition of collision theory?

Collision theory is a fundamental concept in chemistry that explains how chemical reactions occur at the molecular level. It states that for a reaction to take place, reactant particles must collide with each other with enough energy to overcome the activation energy barrier. This energy is necessary to break bonds in the reactants and form new bonds in the products. Therefore, the focus is on the conditions required for effective collisions, which ultimately lead to a chemical change.

Option B captures this essence by emphasizing that chemical reactions can occur when reacting particles collide with sufficient energy. This means that both the frequency of collisions and the energy of those collisions are critical factors in determining whether a reaction will happen. Other choices do not encapsulate the necessary conditions for a reaction in the same way this option does.