Specific energy consumption of an electric train is the ratio between
(A) Specific energy output at driving wheels and efficiency of the traction motor
(B) Specific energy output at driving wheels and efficiency of the transmission gear
(C) Specific energy output of driving motor and efficiency of the driving wheels
(D) Specific energy output at driving wheels and efficiency of the (motor + transmission gear)
(A) Specific energy output at driving wheels and efficiency of the traction motor
(B) Specific energy output at driving wheels and efficiency of the transmission gear
(C) Specific energy output of driving motor and efficiency of the driving wheels
(D) Specific energy output at driving wheels and efficiency of the (motor + transmission gear)