Definition: 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'.
Input: Question: The antitussive dextromethorphan is an enantiomer of the O-methylated derivative of levorphanol that belongs to the structural family of: 
 Options:  <1> 6,7-Benzomorpanos. <2> Morfinanos. <3> 4-Phenylpiperidines. <4> Phenylpropalamine. <5> Oripavinas.
