Which of the following is NOT a tanning effect on skin?

When considering the tanning effects on skin, it's important to understand how each option relates to the exposure to UV radiation.

Wrinkles, dry skin, and solar elastosis are all recognized effects that can result from prolonged or excessive tanning. Wrinkles develop due to the breakdown of collagen and elastin in the skin, which UV exposure can accelerate. Dry skin often results from the depletion of natural oils that occurs with UV exposure, leading to a rough texture and skin flaking. Solar elastosis specifically refers to the degradation of skin elasticity, characterized by changes in the elastic fibers, commonly due to sun damage.

On the other hand, while pimples can occur in various skin conditions and can be influenced by factors such as hormones or bacteria, they are not a direct effect of tanning or UV exposure. Consequently, they do not fall under the umbrella of effects commonly associated with tanning, making this option distinct from the others in the context of skin reactions specifically triggered by tanning.