In this specific scenario, seeing since both of the mediums are differential, the bacteria can grow on either of them, therefore either of them would be a good choice. A differential media allows the researcher to visually distinguish which species have the specific biochemical process. Which in this case both options have the ability to allow bacteria to grow which is what is needed.
Explanation: Well, according to the EPA, point-source pollution is defined as," any single identifiable source of pollution from which pollutants are discharged, such as a pipe etc.." In this example with the paint company, it is identifiable exactly where the pollution had came from hence it being an example of point-source pollution.