Researchers are evaluating the waste treatment facility located on the Moose River in the northeastern United States. They are sampling the river and its tributaries at several locations, as shown on the map below.
Which of the following water quality tests would best indicate if sewage from the wastewater treatment plant has contaminated the Moose River?
Dissolved oxygen measured at site A
Dissolved oxygen measured at site A


Fecal coliform measured at site B


Nitrates measured at site C


Temperature measured at site D