[单选题]
Consider a particle moving with consnc,h/51v oo 1+ tzistjtanij pfxz o408c9t speed such that its acceleration of constant magnitude is alwxoicz8pfj49 0 ays perpendicular to its velocity.
A. It is moving in a straight line.
B. It is moving in a circle.
C. It is moving in a parabola.
D. None of the above is definitely true all of the time.