Inglês — Análise sintática parsing

According to the extract, what is the alternative that contains the right explanation about the gerund in bold type?

Swimming is an amazing exercise. It’s healthy, fun, relaxingand a low-impact sport. I know this from personal experience.Last year while I was jogging I injured my left knee. I don’t gojogging anymore, now I’m considering joining a swimmingcompetition.”

The gerund is: