Assertion (A): Small glass beads fixed on traffic signal glow brightly when light falls upon them.Reason (R) : Light is totally reflected when the angle of incidence exceeds a certain critical value and light travelling in a denser medium is reflected from a rarer medium.Codes:

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are but R is not a correct explanation of A
• C. A is true but R is false
• D. A is false but R is true