In the 1900s, the leading causes of death were due to . bacteria or viruses water pollution environmental factors all of the above

In the 1900s, the leading causes of death were due to bacteria or viruses. It might be said that infectious diseases lead cause of death in the world and in the US. It was after 1950´s that infectious diseases and death rates form these illnesses were reduced. 

This gel or liquid can be placed under the tongue of an unconscious person. this is important because you should never pour anything down the throat of an unconscious person-- s/he could choke.