An Electron Moving Along the +X-Axis Enters a Magnetic Field $\vec { B }$

An electron moving along the +x-axis enters a magnetic field.If the electron experiences a magnetic deflection in the -y direction,then the $\vec { B }$ field must have a component

A) along the +z-axis
B) along the -z-axis
C) along the -x-axis
D) along the +y-axis
E) along the -y-axis