Definition: In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
Input: Question: The reaction of bromine and cyclopentene leads to the production of 1,2-dibromocyclopentane by a mechanism: 
 Options:  <1> Of anti addition. <2> Of addition syn. <3> Substitution SN1. <4> Substitution SN2. <5> Of elimination.
