In a DME system，the Reply Delay is the time interval between the（ ）point on the leading edge of the first pulse of an interrogation pulse pair and the（ ）point on the leading edge of the first pulse of the transponder reply pulse pair.
A.A、1/4 amplitude，1/4 amplitude
B.B、1/3 amplitude，1/3 amplitude
C.C、1/2 amplitude，1/2 amplitude
D.D、1/5 amplitude，1/5 amplitude
正确答案是C