Let \( D = \{ z \in \mathbb{C} \mid |z| < 1 \} \) denote the unit disc in the complex plane \( \mathbb{C} \).
Let \( f: D \to D \) be an analytic function which satisfies \( f(0) = 0 \). Then which one of the following is a possible value of \( f'(0) \)?