Final answer:
HBV and HIV are most commonly transmitted through sexual contact, blood transfusions, and the sharing of needles. Rigorous screening has made transmission through blood transfusions rare in developed countries, and several modes of nonsexual transmission are also possible.
Step-by-step explanation:
HBV (Hepatitis B Virus) and HIV (Human Immunodeficiency Virus) are both commonly transmitted through several routes. These include: 1) Sexual contact, which is the leading cause of HIV transmission globally and involves the exchange of body fluids such as semen and vaginal fluids during intercourse; 2) Blood transfusion, which was a more significant risk before rigorous screening processes were put in place, but is now a rare form of transmission in developed countries; and 3) Sharing needles, which is a common way for viruses to spread among individuals who use intravenous drugs. Therefore, the correct answer would be 4) All of the above. It is important to note that transmission can also occur from an infected mother to her child during pregnancy, at birth, or through breastfeeding, and among healthcare workers via needle-stick injuries.