[单选题]
An object is moving with constalwg ww 87+6( +t5lzajj+i0v z ih3chjhnt non-zm:,ej ,i oyp:pero velocity in the +x axis. The velocity versus time graph ofoye:j: pp,m,i this 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.
