Q: 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: The negative symptomatology of schizophrenia seems to be caused by:
Options: <1> The excessive activity of some dopaminergic neural circuits. <2> The excessive activity of the GABAergic neurons. <3> The existence of brain damage. <4> Have a gene for schizophrenia that causes negative symptoms. <5> Insufficient activity of the serotonergic neurons of the frontal lobe.
A:
3