Which number is represented by the Roman numeral 'X'?

10

What board game involves building railways and stations across various cities in Europe? Who holds the NFL record for most passing touchdowns in a single game? Who was the famous journalist that authored 'The Jungle,' exposing conditions in meatpacking factories? Which president ordered the integration of the U.S. Armed Forces by executive order in 1948? What is the process by which plants make their food?