[单选题]
If the velocity versus f y 6spq s:1vczwv2u):t+v0.o8vo9 pd lt xebv5ime graph of an object is a straight line making an angle of 30 degrees with the time axis, the od 5v xev0oo+pvt.lb98bject is
A. moving with constant non-zero speed.
B. moving with constant non-zero acceleration.
C. at rest.
D. moving with infinite speed.
