I would say using a comma to combine the two sentences.
Answer:
C. In the ancient world, Rome was the center of a powerful empire.
However, it gradually lost its strength, and in 410 CE it was
invaded and practically destroyed. What factors contributed to
Rome's downfall? Why did it find itself unable to defend its own
walls?
Explanation:
The first question asks what the cause of Rome's downfall was. In the second sentence the effect is Rome was invaded and destroyed.
Technically, all of these answers are ways to revise your work. I would go with B, Run a spell check and correct errors because it looks like the most accurate way to edit documents.
C im not sure is is right .
Answer:
Escape Room is a movie that fits that description
There's also this show, Alice In Borderland, it was on Netflix
