In a certain region of space, electric field \( \vec{E} \) and magn...

In a certain region of space, electric field \( \vec{E} \) and magnetic field \( \vec{B} \) are perpendicular to each other. An electron enters perpendicularly to both the field and moves undeflected. The velocity of electron is
(a) \( \frac{E}{B} \)
(b) \( \frac{B}{E} \)
(c) \( \vec{E} \times \vec{B} \)
(d) \( \vec{E} \cdot \vec{B} \)