Assertion (A) Small glass beads fixed on traffic signs start shining rapidly when light is thrown on them? Reason (R) Light is completely reflected when the angle of incidence exceeds a certain critical value and the light passing through a denser medium is reflected from a relatively rarer medium.

• A. Both A and R are correct and R is the correct explanation of A
• B. Both A and R are correct but R and R is not the correct explanation of A.
• C. A is right but R is wrong
• D. A is wrong but R is right