[单选题]
An object is moving wito 1-9e ;b)r8eeayrvasri*;d ah constant no v3j )f+y1an ,;vhxegyn-zero acceleration in the +x axis. The velocity versus time graph of thih n)j+ya,yv1x gef3v;s object is
A. a horizontal straight line.
B. a vertical straight line.
C. a straight line making an angle with the time axis.
D. a parabolic curve.