TASK 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'.
PROBLEM: Question: Which of the following molecules has a simple covalent bond? 
 Options:  <1> C2. <2> N 2 <3> O 2 <4> O 3. <5> F 2

SOLUTION: 5

PROBLEM: Question: The set of means and systems that facilitate the contact of the infectious agent with the recipient subject corresponds to: 
 Options:  <1> Source of infection. <2> Habitat. <3> Transmission mechanism. <4> Biotope <5> Reservoir.

SOLUTION: 3

PROBLEM: Question: The brain alterations that characterize Alzheimer's disease are: 
 Options:  <1> Hyperactivation of the dopaminergic neurons of the basal ganglia, causing neuronal death. <2> Degeneration of the hippocampus, and of the cortex of the frontal and temporal lobes. <3> Deterioration of the serotonergic neurons of the parietal and occipital lobes. <4> Presence of Lewy bodies in all subcortical white matter. <5> Accumulation of denatured prion proteins that cause inflammation in the frontal and parietal lobes.

SOLUTION:
2