The function is in the form of a natural logarithm. We know that the logarithmic function \( \ln(x) \) has a range of \( (-\infty, \infty) \), but since the argument of the logarithm is a ratio between two terms, the range of the function is constrained by the values of \( x \). After evaluating the limits and checking the behavior of the function, we determine that the range of \( f(x) \) is \( (0, 1] \).
The limit: \[ \lim_{x \to 0} \frac{\sin \left( \pi \sin^2 x \right)}{x^2} \] is equal to: