A proton moving with a constant velocity passes through a region of space without any change in its velocity. If $\vec{E}$ and $\vec{B}$ represent the electric and magnetic fields respectively, then the region of space may have :
(A) $\quad E = 0, B = 0$
(B) $\quad E = 0, B \neq 0$
(C) $\quad E \neq 0, B = 0$
(D) $\quad E \neq 0, B \neq 0$
Choose the most appropriate answer from the options given below :
