Explanation:

- Section 26 of the Indian Evidence Act says that a confession made by a person while in police custody is not admissible unless it is made in the immediate presence of a Magistrate.

- Option 1: If made in the presence of a doctor – This does not make the confession admissible under Section 26.

- Option 2: If made in the presence of a captain of a vessel – The captain is not recognized under Section 26.

- Option 3: If made in the presence of a Magistrate – This makes the confession admissible, as per the law. ??

- Option 4: None of the above – Since option 3 is correct, this is not right.