My first assumption was diameter but then thinking about how this is tested I bet it is width, so half circumference.

That means D=4.45” so just over one raccoon, maybe one raccoon and a trinket it found and won’t let go.

I feel like they are probably just guesstimating by using goatse as a source, so diameter?

Any normal person would assume diameter and no-one outside of mathematics would assume radius in this context.