Answer:
C) Incidentally
Explanation:
Personally I don't like any of these answer choices. However, this one makes the most sense in this context. The others would need a much different set-up earlier on in the passage. "Incidentally" does not require such a set up, which is why it is the only one that fits.
1. enemy
2. hall
3. about
4. look like
5. bright
6. land area
7. last name
8. plan
The underlined subject of the sentence the skyscraper that was built last year is a noun phrase.When determining the type of phrase, you first need to find its center, of the most prominent word. Here, the center is skyscraper, which is a noun, which means that the whole phrase is a noun phrase.