A client with red hair and skin type I should be advised that they:

For individuals with red hair and skin type I, it is essential to understand the nature of their skin's response to UV exposure. People with this skin type typically have very fair skin that is highly sensitive to sunlight and UV radiation. They often lack the ability to produce significant amounts of melanin, which is the pigment responsible for tanning.

The correct choice highlights that individuals with this skin type should not expect delayed pigment darkening after exposure to UV light. This means they may not develop a deep or lasting tan; rather, they might experience sunburn or skin irritation instead. Knowledge of this characteristic is critical when advising clients about tanning options, as setting realistic expectations is important for their safety and satisfaction.

In contrast, the other options suggest unrealistic outcomes for individuals with this skin type. Advising that they can tan safely indoors or easily is misleading, as their risk of burns or damage increases due to their low melanin levels. Similarly, suggesting they need higher exposure times could lead to serious skin issues rather than any beneficial tanning effects.