A bit mathematics is involved, but by inspection/observation is more than enough.

better now.

The goose is not directly an index or element of the array, it is the ith person you reach. Try to think in terms of the 'ith' person encountered will be the goose. I think it's a really simple and contrived problem so my explanation is a bit clunky because I'm trying to avoid giving too much away.

Think of the elements as if they're are arranged in a circle.

What happens when you reach the last person in the circle? You're back to the start.
So in the example 5 returns a.name because you've come full circle. Extrapolate on this to understand the rest of the examples.