There are 'm' number of favourable eases to event A and 'n' are non-favourable eases, both are equally likely and mutally exclusive, the probability of occurring the event A is $$P\left( A \right) = \frac{m}{{m + n}}.$$   This formula corresponds to which one of the following approaches to probability?

A. Classical approach to probability

B. Statistical approach to probability

C. Subjective approach to probability

D. Modern approach to probability

Answer: Option A