Suppose there is an infectious disease at a party. how could doctors tell if the disease was foodborne, airborne, or transmitted person to person?

The doctors could simply monitor the symptoms of an infected person. If the infected person sneezes or coughs, then the virus is likely airborne or transmitted from infected surfaces. If no obvious symptoms that would facilitate transmission are detected, the scientists can test for the presence of the virus in the food and drink at the party. 

Your answer is: I will aslo explian it aswell:)
In the burning of natural gas, for example, methane (CH4) and oxygen (O2) are thereactants in the chemical reaction. are the substances formed by a chemical reaction. In the burning of natural gas, carbon dioxide (CO2) and water (H2O) are the products formed by the reaction.
Hoped I helped I learned this in my class:)