Water safety standards in southern California suggest that if a concentration of adenoviruses in the water is more than 1,000 per liter, further testing would have to be done to determine if the water was hazardous. A random sample of 45 water sources around San Diego showed an average of 1,023 adenoviruses per liter, with a standard deviation of 138.9. Which hypothesis test should be used to determine if the water samples contain more than the allowed 1,000 adenoviruses per liter? O z-test for the population mean O t-test for the population proportion O z-test for the population proportion O t-test for the population mean