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 least effective prevention measure in the appearance of an outbreak of salmonellosis is: 
 Options:  <1> Active immunization to the population at risk. <2> Rigorous and frequent hand washing, as well as utensils and surfaces that will be used for cooking. <3> Keep food in the refrigerator. <4> Cook food with sufficient temperature (at least 70ºC). <5> Quick refrigeration of cooked foods.
