If f(x) is a linear function and the domain of f(x) is the set of all real numbers, which statement cannot be true? 1. The graph of f(x) has zero x-intercepts. 2. The graph of f(x) has exactly one x-intercept. 3. The graph of f(x) has exactly two x-intercepts. 4. The graph of f(x) has infinitely many x-intercepts.