Quiz: Optimized Power

In the optimized power function, what do we do when $n$ is even?

1. A.Return $x^2 \\times \\text{power}(x, n-2)$
2. B.Compute $\\text{power}(x/2, n)$
3. C.Return $x \\times \\text{power}(x, n-1)$
4. D.Compute $\\text{power}(x, n/2)$ and square the result