[单选题]
The Michelson-Morley experimenk*h sp5ct +0gnt was designefqbkrdg)(0 xl54in f, 8qbx/td to measure
A. the relativistic mass of the electron.
B. the relativistic energy of the electron.
C. the velocity of the Earth relative to the ether.
D. the acceleration of gravity on the Earth's surface.