Read the paragraph below. Where did the author find the information that some UV radiation is good for you?

Humans need the sun’s light. But another kind of radiation that we can’t see, UV radiation, also comes from the sun. According to the article “What You See Is Not What You Get,” a little UV radiation is good for you: “UV radiation causes the skin to create Vitamin D, which helps people to absorb calcium.” But too much UV radiation can burn your skin or hurt your eyes. That’s why you should use sunscreen. The CDC website tells readers to use at least SPF 15 and to “apply, reapply, and then do it again! …. Put more sunscreen on every couple of hours.”

1.the CDC website
2.The writer already knew this information and did not use a source.
3.both the article and the website
4.“What You See Is Not What You Get”