A particle of mass $m$ and charge $+q$ is shot with velocity $\mathbf{v}$ into a region of uniform magnetic field $\mathbf{B}$. Suppose that $\mathbf{v}$ points to the top of the page and $\mathbf{B}$ points out of the page. Ignoring gravity, the particle
(A) travels in a straight line.
(B) moves clockwise in a circle with radius $r=q B / m v$.
(C) moves counterclockwise in a circle with radius $r=q B / m v$.
(D) moves clockwise in a circle with radius $r=m v / q B$.
(E) moves counterclockwise in a circle with radius $r=m v / q B$.