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: Consider Input: Question: What specific procedure of the experimental strategy makes it the most appropriate to test hypotheses of causality? : 
 Options:  <1> The representative sampling of the participants. <2> The manipulation of the independent variable with control of possible strange variables. <3> The realization of the study in real contexts with natural groups. <4> The identification of possible predictor variables through the retrospective analysis of the study phenomenon. <5> The application of statistical techniques for the analysis of data.

Output: 2


Input: Consider Input: Question: Among the epidemiological criteria of causality defined by Bradford Hill (1965) is NOT: 
 Options:  <1> Strength of association. <2> Temporal sequence. <3> Biological gradient <4> Cessation or reversibility effect. <5> Presence of alternative explanations.

Output: 5


Input: Consider Input: Question: Which of the following strands of DNA has the same nucleotide sequence (except the change of T per U) as its primary transcript? 
 Options:  <1> The leading thread. <2> The Watson strand. <3> The Crick strand. <4> The mold thread. <5> The coding strand.


Output: 5