[单选题]
An object is moving with conszc+g- 7dclq/)s zxwder *2zv.tant non-ze9hag luz7; j3gro acceleration in the +x axis. The position versus time grzh7al j;9 3gguaph of 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.
