When light propagates in vacuum there is an electric field and a magnetic field.

In an electromagnetic wave propagating in vacuum, the electric field (E) and magnetic field (B) are always perpendicular to each other and also perpendicular to the direction of propagation. This is a fundamental property derived from Maxwell's equations. Option A is false because fields oscillate in time. Option B is true on average over a full cycle but not the defining characteristic. Option C is true (transverse wave) but D is more fundamental as it describes both fields' mutual orientation.