Final answer:
If the kinetic energy of reactants is insufficient to meet the activation energy requirement, an activated complex will not form, the reactants will remain unchanged, and the reaction rate will decrease.
Step-by-step explanation:
If the kinetic energy of the reactants is not high enough to provide the needed activation energy, the reaction will not proceed as the collisions between reactant molecules will not be forceful enough to overcome the energetic barrier. In this scenario, without the necessary activation energy, the reactants will not form an activated complex, and consequently, the reaction will not yield products. Instead, the reactants would continue to exist in their present state, and the rate of the reaction would tend to decrease, not increase, since fewer energetic collisions are occurring.