By tar, I think you mean nicotine. (I Hope). It affects the nerve signals that regulate breathing.
Es | HIV.gov
There is currently no vaccine available that will prevent HIV infection or treat those who have it. However, scientists are working to develop one.
Answer:
Mechanically - By the action of a force.
Electrically - By an electrical current.
By radiation - By Light waves or Sound waves.
By heating - By conduction, convection or radiation.
Explanation:
Because our bodies work to fight off unknown substances like bacteria
