Read the sentence. conservationists are considering urban runoff and they are tracking population growth but the magnitude of the situation has not been determined. according to the elements of style, what is the correct way to punctuate this sentence?

The correct way to punctuate the sentence is:

Conservationists are considering urban runoff and they are tracking the population growth but, the magnitude of the situation has not been determined.

Commas are placed in between phrases in order for the reader to have a short pause on the thought of the sentence being conveyed. A period is placed in the end of a sentence to connote that the thought has been finished.