Assertion(A): A rainbow is formed when white light is incident on raindrops.
Reason(R): White light contains seven colours and it undergoes dispersion inside a raindrop.
Both A and R are correct, and R is the correct explanation of A.
Explanation for Assertion statement: A rainbow is nothing but a multicolored arc which we see after the rain when light is incident on raindrops.
Explanation for Reason statement: We all know that the white light contains many colors mainly the "VIBGYOR".So when white light is incident on a raindrop dispersion(separation of light into VIBGYOR) of light takes place and due to total internal reflection and refraction of light, we see a rainbow.
Therefore, the assertion and reason both are true and the reason is the correct explanation of the assertion.
Hence, option (A) is the correct answer.