Assertion (A): The amount of photoelectric emission depends on the intensity of incident light. Reason (R): Photo electric emission can occur only if frequency of incident light is less than threshold frequency.

• A. Both A and R are true and R is correct explanation of A
• B. Both A and R are true 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