Jen Has Fair Skin, and Both Her Mother and Her

Jen has fair skin, and both her mother and her aunt have been treated for skin cancer. This coming weekend, Jen and her friends are planning an all-day outdoor hike near a high-mountain lake; she expects there will be a mix of sun and shade on the trail and at the lakeshore beach. She is looking forward to the hike, but she wants to avoid getting a sunburn or any sun damage. Jen is wearing a shirt with a UPF rating of 25. This means

A) Jen can stay in the sun for 25 minutes without getting burned.
B) Clothing does not have UPF ratings.
C) Jen's shirt has the highest UPF rating ("excellent") .
D) Jen can stay in the sun without getting burned for 25 times longer than if she were wearing a standard T-shirt.