You will be given a definition of a task first, then some input of the task.
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'.

Question: Which of the following multivariate analysis techniques analyzes the covariation presented by a set of metric variables, susceptible of being synthesized in a set of common factors that lie behind them?
Options: <1> Multiple discriminant analysis. <2> Multiple linear regression <3> Multivariate analysis of variance. <4> Factorial analysis. <5> Analysis of structural equations.
Output:
4