Correct answer: Transverse EM wave (Option C).Solar radiation is electromagnetic radiation emitted by the Sun, consisting of visible light, ultraviolet, infrared, and other electromagnetic waves.Electromagnetic waves are produced by oscillating electric and magnetic fields, denoted by E and B, which are mutually perpendicular and also perpendicular to the direction of propagation.Therefore, electromagnetic waves are transverse in nature — they are transverse EM waves.They are not mechanical waves, since mechanical waves (like sound) require a material medium, whereas solar radiation travels through the vacuum of space.They are not stationary waves, since a stationary (standing) wave is formed by the superposition of two identical waves travelling in opposite directions, which is not the case for radiation propagating from the Sun.They are not longitudinal EM waves, because a longitudinal wave has oscillations along the direction of propagation, which does not occur for electromagnetic radiation.Hence, solar radiation is a transverse EM wave, i.e. Option C.