For a plane electromagnetic wave propagating in x-direction, which one of the following combination gives the correct possible directions for electric field (E) and magnetic field (B) respectively?

The ratio of contributions made by the electric field and magnetic field components to the intensity of and electromagnetic wave is : (c = speed of electromagnetic waves)

Which colour of the light has the longest wavelength?

An EM wave is propagating in a medium with a velocity $$\overrightarrow v = v\widehat i$$. The instantaneous oscillating electric field of this em wave is along +y axis. Then the direction of oscillating magnetic field of the em wave will be along