单项选择题

设两电流分别为i1=5sin(Πt+3Π/4)A,i2=4sin(Πt-Π/2)A,,则i1对i2的相位差为()

A.超前Π/4rad
B.滞后3Π/4rad
C.滞后Π/4rad
D.超前3Π/4rad