AIIMS 2018 Physics Wave Velocity Assertion Reason Question

Option B is correct because the assertion that the velocity of electromagnetic waves depends on the electric and magnetic properties of the medium is true; for example, in materials, the speed is influenced by permittivity (ε) and permeability (μ). However, the reason stating that the velocity of electromagnetic waves in free space is constant does not explain the assertion, as it pertains specifically to a vacuum where the speed is approximately 3 × 10⁸ m/s, independent of medium properties. Option A is incorrect because the reason does not provide a correct explanation for the assertion. Options C and D are also incorrect since both the assertion and reason are true, but they do not relate as a cause and effect.