The question given below consist of an assertion (A) and a reason ( R). Use the following key to choose the appropriate answer to these questions from the codes (a), (b), ( c) and (d) given below:
(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) A is false and R is also false.
Assertion: A convex lens of focal length 30 cm and can't be used as a simple microscope in normal setting.
Reason: For normal setting, angular magnification of simple microscope is `M=D//F`.