Ans. A: Heterosexual Intercourse. Heterosexual Intercourse is the most common route but the chance of infection is less (0.30%) ,looking to the other options. Average per act risk of getting HIVby exposure route to an infected source Exposure routeChance of infection Blood transfusion 90% Childbih (to child) 25% Needle-sharing injection drug use 0.67% Percutaneous needle stick 0.30% Receptive anal intercourse* 0.04-3.0% Inseive anal intercourse* 0.03% Receptive penile-vaginal intercourse* 0.05-0.30% Inseive penile-vaginal intercourse* 0.01-0.38% Receptive oral intercourse*SS 0-0.04% Inseive oral intercourse*SS 0-0.005% * assuming no condom useSS source refers to oral intercourseperformed on a man Most commonly, people get or transmit HIV through sexual behaviors and needle or syringe use. MC mode of transmission: Hetero-sexual In hetero-sexual transmission: Male to female is commoner (as compared to female to male) Chances of transmission with accidental needle prick: 0.3%. Less commonly, HIV may be spread From mother to child during pregnancy, bih, or breastfeeding. Although the risk can be high if a mother is living with HIV and not taking medicine, recommendations to test all pregnant women for HIV and sta HIV treatment immediately have lowered the number of babies who are born with HIV. In extremely rare cases, HIV has been transmitted by Oral sex--putting the mouth on the penis (fellatio), vagina (cunnilingus), or anus (rimming). In general, there's little to no risk of getting HIV from oral sex. Receiving blood transfusions, blood products, or organ/tissue transplants that are contaminated with HIV. This was more common in the early years of HIV, but now the risk is extremely small because of rigorous testing of the blood supply and donated organs and tissues. Eating food that has been pre-chewed by an HIV-infected person. The contamination occurs when infected blood from a caregiver's mouth mixes with food while chewing. The only known cases are among infants. Being bitten by a person with HIV. Each of the very small number of documented cases has involved severe trauma with extensive tissue damage and the presence of blood. There is no risk of transmission if the skin is not broken. Contact between broken skin, wounds, or mucous membranes and HIV-infected blood or blood-contaminated body fluids. Deep, open-mouth kissing if both paners have sores or bleeding gums and blood from the HIV-positive paner gets into the bloodstream of the HIV-negative paner. HIV is not spread through saliva.