What is a primary benefit of using a booster or accelerator in tanning?

A primary benefit of using a booster or accelerator in tanning is that it balances the skin's pH for a darker tan. This is crucial because the skin's pH level can significantly influence the effectiveness of tanning products. An optimal pH level helps the tanning agents to work more efficiently, allowing for a deeper and more even tan. By maintaining or adjusting the skin's pH, boosters or accelerators enhance the tanning process, leading to better results.

The other options do not align directly with the primary benefits associated with boosters or accelerators. While some tanning products may be moisturizing, that is not the main function they serve. Additionally, achieving immediate color can relate more to self-tanning products rather than the function of boosters or accelerators. Therefore, the benefit of balancing skin's pH stands out as a key aspect of what these products are designed to accomplish in the tanning process.