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.

Read the following passage: he roamed from chamber to chamber with hurried, unequal, and objectless step. the pallor of his countenance had assumed, if possible, a more ghastly hue— but the luminousness of his eye had utterly gone out. the once occasional huskiness of his tone was heard no more; and a tremulous quaver, as if of extreme terror, habitually characterized his utterance. there were times, indeed, when i thought his unceasingly agitated mind was laboring with some oppressive secret, to divulge which he struggled for the necessary courage. which of the above ideas might be considered foreshadowing? he is wandering all over the chamber his skin tone is really pale his voice is quivering the narrator thinks he is laboring with an oppressive secret