Dominic has contracted HIV. What was MOST likely the cause of this virus?

He inhaled droplets from a close friend’s sneeze
.He didn’t thoroughly wash his hands after using the restroom.
He shared a dirty needle when injecting drugs with a friend.
He consumed food that wasn’t cooked to a safe temperature.

The most likely cause of Dominic contracting HIV would be sharing a dirty needle when injecting drugs with a friend. HIV is primarily transmitted through unprotected sexual intercourse and sharing needles or syringes with an infected person.