Which three elements are essential for producing a tan?

The elements essential for producing a tan primarily involve types of ultraviolet (UV) radiation, specifically UVA and UVB. These two types of UV light interact with the skin to stimulate the production of melanin, which is the pigment responsible for skin color.

UVB rays are known to be the primary cause of sunburn and play a significant role in the production of vitamin D, while UVA rays penetrate the skin more deeply and contribute to the tanning process. Oxygen is also crucial as it is a vital component for cellular metabolism and overall skin health, facilitating the skin's response to UV exposure and the tanning process itself.

The other options include elements that do not play a direct role in tanning. For example, UVC rays are largely absorbed by the Earth's atmosphere and do not reach the skin; visible light does not contribute to the tanning process either. Water is important for skin hydration but is not a direct factor in melanin production or tanning. Therefore, the combination of UVB, UVA, and oxygen presents a comprehensive understanding of the tanning process.