Why Are Two Electrodes Usually Used to Record the Electromyographic

Why are two electrodes usually used to record the electromyographic signal at the skin surface?

A) In case the signal from one of the electrodes is lost
B) Because the amplifier subtracts the signal from one electrode from the other, thus removing noise from the recorded signal
C) To record the signal from a greater number of motor units
D) To reduce the effect of cross-talk
E) To reduce skin resistance