If it is improperly introduced into the environment, acid-whey runoff can pollute waterways, depleting the oxygen content of streams and rivers as it decomposes.
question 11 options:

no change

can pollute waterway's,

could have polluted waterways,

has polluted waterway’s,

No change

I hope that this is the right answer for you.

true. the definition explains it: a word or phrase that modifies or qualifies an adjective, verb, or other adverb or a word group, expressing a relation of place, time, circumstance, manner, cause, degree, etc. this is a dictionary definition that i have looked up in a dictionary.

scholarship is an sc because, by definition, a subject complement is the adjective, noun or pronoun that follows a linking verb, for example the verb be (in any of its forms).