What are electromagnetic waves composed of?

Electromagnetic waves are composed of transverse waves characterized by oscillating electric and magnetic fields that are perpendicular to each other and to the direction in which the wave travels. This unique structure allows electromagnetic waves to propagate through a vacuum as well as through various media, without the need for a physical medium, which differentiates them from mechanical waves.

In contrast, sound waves are longitudinal waves that require a medium (like air, water, or solid materials) to travel. Longitudinal waves exhibit compressions and rarefactions along the same direction as the wave is moving, which is fundamentally different from the transverse nature of electromagnetic waves. Mechanical waves also require a medium to propagate, which again sets them apart from electromagnetic waves, making option B the only accurate description of their composition.