In an Economy Whose Real National Income Is £200 Million

In an economy whose real national income is £200 million (measured in base- year prices) , whose velocity of circulation is 8 and where the price index in base- year prices is 2, the money supply must be

A) £40 million.
B) £12.5 million.
C) £800 million.
D) £20 million.
E) £50 million.