Final answer:
Option A. Injecting drugs is most commonly associated with Hepatitis C (HCV) due to the direct exposure to infected blood through needle sharing. Hepatitis B and D also involve blood-borne transmission, but Hepatitis C is considered the primary risk related to drug injection.
Step-by-step explanation:
Injecting drugs is thought to be the single most important risk factor for Hepatitis C (HCV). While all hepatitis viruses can cause similar symptoms due to their impact on liver cells, their transmission methods vary. Hepatitis A and E are typically contracted through ingestion, but Hepatitis B, C, and D are transmitted through parenteral contact, such as exposure to infected blood or body fluids.
Hepatitis B (HBV) is particularly associated with exposure to infectious blood and can be a significant occupational hazard for health-care workers despite vaccination efforts. Hepatitis D (HDV) can only occur in patients already infected with HBV. However, the most common hepatitis virus associated with injection drug use is Hepatitis C, as it is primarily spread through the sharing of needles or other equipment used to inject drugs. This method bypasses the body's normal defenses by injecting the virus directly into the bloodstream.