Explanation
The correct answer is (b) Virus.
AIDS (Acquired Immunodeficiency Syndrome) is caused by the human immunodeficiency virus (HIV), which belongs to the group of viruses called retroviruses. HIV infects and gradually weakens the immune system, leaving individuals more susceptible to various infections and diseases. HIV is primarily transmitted through unprotected sexual contact, sharing contaminated needles, mother-to-child transmission during childbirth or breastfeeding, and less commonly through blood transfusions (in regions without proper screening) or organ transplantation.
It's important to note that AIDS is not caused by bacteria, fungi, or protozoa, but specifically by the HIV virus.
