It all depends on your interpretation of what the radius is. A radius of 2 could mean two stars, or it could mean a distance of two (in which case the middle row should have one star in the middle, with two stars on each side).

We don't really care which interpretation you choose, just make sure that your Circle object draws something close to a Circle, and that the bigger it is the closer to a circle it is. No shortcuts (rounded rectanges, etc)!