A : An exact number has infinite number of significant digits.
R : A number, which is not a measured value has infinite number of significant digits.

Options

A. Both (A) and (R) are true and (R) is the 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. Both (A) and (R) are false

Answer

B