In electric traction for a trapezoidal speed-time curve, the time period is
(A) free running speed period = constant speed period
(B) free running period = coasting period
(C) free running period + coasting period = constant speed period
(D) average speed period = scheduled speed period
(A) free running speed period = constant speed period
(B) free running period = coasting period
(C) free running period + coasting period = constant speed period
(D) average speed period = scheduled speed period