Which of the following is NOT a known trigger for acne?

Frequent exercise is not considered a direct trigger for acne. While engaging in regular physical activity is generally associated with numerous health benefits, including improved circulation and hormonal balance, it does not inherently cause or exacerbate acne.

On the other hand, hormonal changes can lead to increased oil production in the skin, which can contribute to acne development. Dietary choices have also been linked to acne, especially foods with high glycemic indexes or dairy products. Stress is known to exacerbate acne as well, as it can lead to hormonal fluctuations and inflammation. Therefore, among the options listed, frequent exercise stands out as not being a recognized trigger for acne.