The correct option is D Can not be determined
If an experiment results in a total of (m+n) outcomes which are equally likely and if m outcomes are favorable to an event A, while n are unfavorable, then the probability of occurrence of the event A, is given by P(A)=m(m+n). This is how we calculate probability using classical definition of probability. To apply this, the outcomes have to be equally likely. In this question, it is not given they are equally likely. If the events were equally likely, probability of A would come out to be 510=0.5 Since its not given they are equally likely, we can't find the probability.