Which of the sentences below is an example of a run$-$on$?$

A run$-$on sentence doesn't necessarily need to be long to be a run$-$on$.$

My favorite brand of candy is Reese's Peanut Butter Cups, because they are absolutely delicious and can't be beat.

This sentence is a run$-$on$.$ Because it goes on and on$.$

When he goes to the gym, he sees a lot of people who aren't serious about getting fit they just come for the social aspects of the gym.