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: The reduction of nitriles with diisobutyl aluminum hydride (DIBAL) provides, after the corresponding aqueous acid treatment:
Options: <1> Amines <2> Acids <3> ketones. <4> Aldehydes. <5> None of the above.
4