Which sentence does not contain any errors in comma usage? A. In a pool or at a beach, lifeguards are often on duty. B. In a pool, or at a beach, lifeguards are often on duty. C. In a pool, or, at a beach, lifeguards are often on duty. D. In a pool or at a beach lifeguards are often on duty. A?!
I actually think this one is A.
Because you say it with a pause before "or".
It can't be C, because C has no commas, and commas are definitely needed for this sentence.
B is close, but it needs one more comma
