Assertion (A): Speed of light outside the prism is different from inside the prism.
Reason (R): A beam of white light gives a spectrum on passing through a glass prism.
a) Both A and R are true, and R is the correct explanation of A.
b) Both A and R are true, but R is not the correct explanation of A.
c) A is true, but R is false.
d) Both A and R are false.