Instructions: 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: A compound that has a five-membered aromatic heterocyclic skeleton with three carbon atoms and two nitrogens, the latter being positions 1 and 3, is called:
Options: <1> Pirrol. <2> Pyrimidine <3> Pyrazole <4> Pyrazolidine. <5> Imidazole
Output:
5