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: Which of these characteristics do bacterial exotoxins have ?: 
 Options:  <1> They have all the Gram negative bacteria. <2> They are lipidic in nature. <3> They are located in the outer membrane. <4> They introduce a weak immune response. <5> Some are used inactivated as a vaccine.
