The correct answer to the question is D. Electromagnetic waves.
EXPLANATION:
As per the diagram, the radiations are emitted by sun is coming to earth.
The radiations coming from sun is electromagnetic in nature. It does not require any medium for its propagation. It travels a long distance in vacuum or space to reach earth.
It contains both electric field and magnetic field which are perpendicular to each other and also normal to the direction of propagation. The diagram shows that the wave is moving in the form of crests and troughs.
If we consider the wave nature of radiation, then it is one way of transportation of thermal energy from sun to earth which is known as radiation.
Hence, the arrows drawn in the figure is electromagnetic waves.
