Assertion (A): For a physically realisable driving point function, the degree of numerator and denominator should be equal.Reason (R): The sum of positive real functions is real.

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