The correct option is A Blood transfusion
HIV (Human Immunodeficiency Virus) is the causative agent of AIDS. HIV is spread from an infected person to another person through direct contact with some of the body’s fluids like mother milk, blood, lymph and semen through sexual intercourse or by sharing the drug equipment like needles or from mother to child during childbirth or breastfeeding or via blood transfusion.
Thus, the correct answer is option A.