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: What alteration does a person suffer that believes that their thoughts are not theirs but have been introduced into the mind by an external and irresistible force ?:
Options: <1> Obsessive idea <2> Delusional idea of denial. <3> Fugue of ideas. <4> Delirium to be controlled. <5> Echo of thought.
Output:
4