Answer:
Radiation
Step-by-step explanation:
For about the last 5 billion years, the sun has been fusing light elements into heavier ones, and creating lots of energy in that process. After about 100,000 years, that energy gets to the surface of the sun in the form of electromagnetic radiation, in which form it travels all the way to earth, through the atmosphere, and then onto the skin of people tanning. Hope this helps!