A Positively Charged Particle Moves with Velocity V Along the +X-Axis

A positively charged particle moves with velocity v along the +x-axis. A uniform magnetic field B exists in the negative z direction. You want to balance the magnetic force with an electric field so that the particle will continue along a straight line. The electric field should be in the

A) positive x direction.
B) positive z direction.
C) negative y direction.
D) negative x direction.
E) negative z direction.