I believe a pot of water that is being heated by a electric burner. This is because the warmer water moves to the top and the cooler water moves down to the bottom of the pot. This causes a circular motion. The next example of convection heat is a hot air ballon rising and falling in the atmosphere. A radiator is also because the hot air is drawn out the top and the cooler air is drawn to the bottom.
HIV directly attacks CD4 helper lymphocytes directly. (D)
Answer: Point-Source
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.