Which of these illustrates rome's legacy in our modern world?

Greek language is used little outside Greek (some small pockets in the ancient major cities), so it's not that. The Orthodox Church has no one center, no one supreme leader except Christ, who is not in Rome per se, so it's not that. We wear Roman clothes only to costume parties, so it's not that. Many of Europe's roads and parts of its water systems have been around for 2000 years. 

Christ is Risen! 
/Orthodox

Delaware, pennsylvania, new jersey, georgia, connecticut, massachusetts bay, maryland, south carolina, new hampshire, virginia, new york, north carolina, and rhode island and providence plantations where the 13 original colonies