Assertion: Electromagnetic waves are transverse in nature
Reason: The electric and magnetic fields in electromagnetic waves are perpendicular to each other and to the direction of propagation.
(A) Both assertion and reason are correct and reason is the correct explanation of assertion.
(B) Both assertion and reason are correct but reason is not the correct explanation of assertion.
(C) Assertion is correct but reason is incorrect.
(D) Both assertion and reason are incorrect.

Hint: The electromagnetic waves are formed when the electric field couples with the magnetic field. The direction of the propagation of electromagnetic waves is perpendicular to both electric as well as magnetic field and moreover the electric and the magnetic field are also perpendicular to each other.

Complete answer:
A wave is said to be transverse in nature if the particles in the medium oscillate due to the wave oscillates in a direction perpendicular to the direction of propagation of the wave.
When an electric field vector and magnetic field vector oscillate together, it forms a wave. This wave composed of an electric field vector and the magnetic field vector is called an electromagnetic wave. In the electromagnetic wave, the electric field and magnetic field are oriented in such a direction that they are perpendicular to each other and also perpendicular to the direction of propagation of the wave. Due to the perpendicular directions of the electric and magnetic fields to each other and also to the direction of propagation of the wave, the electromagnetic wave is transverse in nature. Therefore, the assertion and reason given are both correct and reason is the correct explanation for the assertion.

Hence, the correct option is A.

Note: For a wave to be transverse in nature, it should oscillate the particles of medium in a perpendicular direction to the direction of propagation of the wave. It might then be confusing, what is the relation of being electric and magnetic field perpendicular to direction of propagation of the wave. Actually, the direction of transfer of energy should be transverse which is satisfied by the electromagnetic wave. Hence, it is transverse in nature.