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: Graphite is a conductor because:
Options: <1> The valence band has electronic vacancies. <2> The driving band has electronic vacancies. <3> Both bands have electronic vacancies. <4> The banned band is very big. <5> The band gap is zero.
5

Question: In the activation of the serum complement, the assembly of the Membrane Attack Complex begins with:
Options: <1> C9 <2> C5b. <3> C3a. <4> C6 <5> C8.
2

Question: A group of researchers conducted a prospective study to evaluate the efficacy of three alternatives in the treatment of acute otorrhea in children with tympanostomy tubes. Randomized, 76 children received oral amoxicillin-clavulanic acid, 77 received ear drops with hydrocortisone-bacitracinacolistin and other 77 children did not receive any pharmacological treatment, only observation. The main variable was the presence of otorrhea. What kind of study is it?
Options: <1> Cohort study. <2> Post-authorization study of prospective follow-up. <3> Post-authorization study linked to the authorization. <4> Clinical trial <5> Transversal study.
4