The SI Unit of Length, the Meter, Is Currently Defined

Multiple Choice

The SI unit of length, the meter, is currently defined

A) as the length of the path traveled by light in a vacuum during 1/299792485 s.
B) as the distance between two marks on a metal bar make of a platinum-iridium alloy kept at the National Bureau of Standards.
C) by the President's foot.
D) as 10^-7 of the distance from the North Pole to the equator along a meridian running through Paris.
E) 1,553,164.1 wavelengths of red cadmium light in dry air at 25°C.