Which of the Following Is a Reason for London's Dominance

Which of the following is a reason for London's dominance in the foreign exchange market?

A) Great Britain's decision to retain the British pound instead of using the euro
B) The preeminence of Financial Times Stock Exchange (FTSE) index as an economic health indicator
C) London's location making it the link between the East Asian and New York markets
D) London being the preferred headquarters destination for major multinational corporations
E) London's trading centers opening soon after Tokyo's and New York's trading centers closing for the night