The river had been polluted for decades ______ but the cleanup effort, led by a coalition of local groups, has restored it to near-pristine condition.
Which choice completes the text so that it conforms to the conventions of Standard English?
- A
(empty)
- B
:
- Ccheck_circle
,
- D
;
Explanation
Two independent clauses joined by "but" take a comma before "but."