Among the choices, the only complete sentence is the second choice, "B. He could not wait lang. This is a complete sentence because the thought is already complete. All the rest of the choices did not express complete thought. The subject and the predicate are also connected by a linking verb.
B. It has a comma after "all right" and "P.M." is correctly written. It has dots after the letters bc it's an abbreviation.
I think I’d need the passage to answer.