Question 3 of 5
A scientist discovers that the turbidity of a river increased
over time. At the same time, its population of frogs grew
much smaller. When the turbidity of the river returned to
normal, the frog population recovered.
In what two ways can the frog population be used to monitor the river's water
quality?
A. It can indicate that the water is polluted.
B. It can indicate when the cloudiness of the water is too high.
C. It can be used to change the pH.
O D. It can be used to test for nitrates.