An 18-year-old patient presents to the ED, brought by his mother after about 2 months of worsening paranoid delusions and hearing voices. On exam he is found to be alert without signs of depression and has disorganized speech and auditory hallucinations. Screen for drugs of abuse is negative. What is the MOST appropriate diagnosis?
(A) Schizophrenia.
(B) Schizophreniform disorder.
(C) Brief psychotic disorder.
(D) Delirium.