[单选题]
Consider a particle moving with coijs fn3 7d,n9jnstant speed such that itsu5gw3m q 6whx5 acceleration of constant magnitude is always perpendicular to its vhxu 6 m53gwqw5elocity.
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.
