Which of the following is a sign of skin irritation?

Redness is a key indicator of skin irritation. When the skin experiences irritation, whether from allergens, irritants, or other factors, it often responds by increasing blood flow to the affected area, which results in visible redness. This reaction serves as a protective mechanism, signaling to the body that there is a problem that needs to be addressed.

In contrast, wrinkles are typically associated with aging and loss of collagen and elasticity, while dark spots are often linked to hyperpigmentation due to sun exposure or hormonal changes. Firmness is a characteristic related to the overall health and elasticity of the skin, not directly indicating irritation. Understanding these distinctions helps in identifying and addressing skin concerns effectively.