Alcohol use. I know for a fact that that's the answer.
HIV crossed from chimps to humans in the 1920's in what is now the Democratic Republic of Congo. This was probably as a result of chimps carrying the Simian Immunodeficiency Virus (SIV), a virus closely related to HIV, being hunted and eaten by people living in the area.
C) The technician may be asked by the patient to interpret the images.
