This question presents a sentence. The underlined parts of the sentence might display errors in grammar, correctness, and style. Choice 'A' repeats the underlined part as-is -- meaning that it is the best and most correct expression. The other four choices present other options. When evaluating your choices, choose the one that is most effective, grammatically correct, and precise and follow the conventions of standard written English.
We saw many photographers at the Grand Canyon with cameras, as they were waiting for the sunset.