If a rational number \(\frac{a}{b}\) is a prime number, where \(a\) and \(b\) are positive integers, and \(b\) is not equal to 1, what can we say about the value of \(a\)?

Step 1 ：Since \(\frac{a}{b}\) is a rational number, \(a\) and \(b\) are integers and \(b\) is not equal to 0.

Step 2 ：Given that \(\frac{a}{b}\) is a prime number, it can only have two distinct positive divisors.

Step 3 ：However, if \(b\) is not equal to 1, then \(\frac{a}{b}\) will have more than two distinct positive divisors, which contradicts the definition of a prime number.

Step 4 ：Therefore, the only possibility is that \(a\) is equal to 0.