A 38-year-old unemployed woman with a history of injection drug use and frequent binge drinking presents

A 38-year-old unemployed woman with a history of injection drug use and frequent binge drinking presents to a hepatologist for a new diagnosis of hepatitis C. Five years ago she had a severe postpartum hemorrhage requiring transfusion of 4 units of packed red blood cells. She reports numerous sexual partners in the past, but has had the same male partner for the last five years. She has two elaborate tattoos and several piercings, which were done by a friend that owns a state regulated parlor. What is her most significant risk factor for Hepatitis C? History of injection drug use. History of numerous sexual partners. History of tattoos and piercings. History of blood transfusion. History of binge drinking.