Which of the following is NOT a mode of transmission of AIDS?

The correct answer is Option (4) → Mere touch or physical contact

AIDS is caused by the Human Immunodeficiency Virus (HIV). HIV passes from one person to another through body fluids: by sexual contact with an infected person, by transfusion of contaminated blood and blood products, by sharing infected needles, and from an infected mother to her child through the placenta. It is not spread by mere touch or physical contact.

Option (1) Use of contaminated hypodermic needles — A mode of transmission of AIDS. Shared infected needles, as among intravenous drug abusers, carry the virus in blood.

Option (2) Contaminated blood transfusion — A mode of transmission of AIDS. Transfusion of contaminated blood or blood products passes HIV directly into the bloodstream.

Option (3) Organ transplantation — A mode of transmission of AIDS. An organ from an infected donor carries the donor’s blood and body fluids, so HIV can pass to the receiver, as in a blood transfusion.

Option (4) Mere touch or physical contact — Not a mode of transmission of AIDS. Touch involves no exchange of body fluids, so HIV is not passed this way.

NCERT Extract:
AIDS – “… AIDS is caused by the Human Immuno deficiency Virus (HIV), a member of a group of viruses called retrovirus, which have an envelope enclosing the RNA genome (Figure 7.6). Transmission of HIV-infection generally occurs by (a) sexual contact with infected person, (b) by transfusion of contaminated blood and blood products, (c) by sharing infected needles as in the case of intravenous drug abusers and (d) from infected mother to her child through placenta.”
AIDS – “… It is important to note that HIV/AIDS is not spread by mere touch or physical contact; it spreads only through body fluids.”