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'.
Q: Question: The following are obtained only by chemical synthesis:
Options: <1> Penicillins <2> Cephalosporins. <3> Macrolides <4> Aminoglycosides <5> Quinolones
A:
5