Question 216·Hard·Standard English Conventions

Start by sorting the verb forms by number, meaning whether they go with one thing or more than one. Illuminates, is illuminating, and has illuminated are singular forms: each works after it. The blank follows catacombs that, so we need the number of the noun that that stands for. The different tenses don’t settle that question.

Which noun does that stand for? Beneath the monument lie catacombs puts the subject after the verb, so flip the opening: the catacombs lie beneath the monument. The monument names the place, while the catacombs are the things located there. The following that begins a clause, a group of words with its own subject and verb, and points back to the catacombs. That’s the noun whose number controls the blank, even though it comes after lie.

Does together with a recently cataloged artifact collection make the collection part of the subject? No: together with adds extra information between commas, not a second subject joined by and. Cross that phrase out, and the describing part is about the catacombs alone. Since there’s more than one catacomb, the subject is plural, which means we can replace it with they.

Which form works after they, our stand-in for catacombs? The check gives they illuminate, so the matching form is illuminate. This gives a plural verb for the part describing the catacombs. Choice A.