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Correct answer: A. 0 ≤ P ≤ 1
The probability of an event $E$, denoted as $P(E)$, is defined as the ratio of the number of favorable outcomes to the total number of outcomes in a sample space.
1. **Minimum Value**: The smallest number of favorable outcomes is $0$ (this happens when the event is impossible). Therefore, the minimum probability is:
$$P(E) = \frac{0}{n} = 0$$
2. **Maximum Value**: The largest number of favorable outcomes is equal to the total number of outcomes $n$ (this happens when the event is certain). Therefore, the maximum probability is:
$$P(E) = \frac{n}{n} = 1$$
3. **Conclusion**: Since the number of favorable outcomes $m$ must satisfy $0 \leq m \leq n$, it follows that dividing by $n$ gives:
$$\frac{0}{n} \leq \frac{m}{n} \leq \frac{n}{n}$$
$$0 \leq P(E) \leq 1$$
Thus, the probability of any event must be between 0 and 1, inclusive.