Scorekeeper confused

So my dad was doing the scorebook for my little brothers team last night, and he came to me with a question about a play.

Runners on first an second, one down, kid hits a single into short right field. 100% a legit single. However, the runner on second thought it was gonna be caught so he stayed on the base. The fielder recognized the base running mistake, and throws to third and gets the force out.

Is this still scored as a single, and a 9-5 putout, or does it get scored as a fielders choice because there was a force out?