Hi! The sentence you gave is a complex sentence. For a sentence to be compound, it should contain multiple subjects or predicate. On the other hand, for it to be complex, a subordinate clause must be present.
We can notice that the clause "that were built under the city" is a clause that cannot stand alone thus this will tell us that the sentence is complex.
ANSWER: D. Complex
Answer: *the cafeteria was crowded,so I had to eat outside
*my mom likes to cook spaghetti and it's one of my least favourite meal
*it has been raining all week,for I am ready for a sunny day
* the noise in the classroom was too much, so my teacher asked us to be quieter
Explanation:
