Task: Question Answering
Input (English): Question: The molecularity of an elementary reaction corresponds: 
 Options:  <1> At the initial concentration of reagent. <2> To the number of molecules that are found to react. <3> To the number of collisions of the reactants per unit of time. <4> At the final concentration of the product. <5> To the reaction between the reaction rate and the reagent concentration.
Output (English): 2