Question: If $f(x) = x^2 - 2x + 1$ and $g(x) = x + 2$, then $f(g(-1)) = ______$.
1. **State the problem:** We need to find the value of the composite function $f(g(-1))$ given $f(x) = x^2 - 2x + 1$ and $g(x) = x + 2$.
2. **Recall the definition of composite functions:** $f(g(x))$ means we first find $g(x)$ and then substitute that result into $f$.
3. **Calculate $g(-1)$:**
$$g(-1) = -1 + 2 = 1$$
4. **Substitute $g(-1)$ into $f(x)$:**
$$f(g(-1)) = f(1) = 1^2 - 2(1) + 1$$
5. **Simplify the expression:**
$$f(1) = 1 - 2 + 1 = 0$$
6. **Final answer:**
$$f(g(-1)) = 0$$
Therefore, the correct choice is d.) 0.