A charged particle with charge `q` enters a region of constant, uniform and mututally orthogonal fields `vec(E) and vec(B)` with a velocity `vec(v)` perpendicular to both `vec(E) and vec(B)`, and comes out without any change in magnitude or direction of `vec(v)`. Then
A. `vec(v)=(vec(E) xxvec(B))//B^(2)`
B. `vec(v)=(vec(B) xxvec(E))//B^(2)`
C. `vec(v)=(vec(E) xxvec(B))//E^(2)`
D. `vec(v)=(vec(B) xxvec(E))//E^(2)`
