Final answer:
The primary cause of almost 90% of skin's wrinkles is sun exposure, which damages collagen fibers and accelerates aging. Overexposure can result in skin cancer and the formation of wrinkles due to structural breakdown in the skin.
Step-by-step explanation:
Almost 90% of the skin's wrinkles are caused by sun exposure. Extensive research has shown that all UV radiation can damage collagen fibers and accelerate the aging process of the skin, leading to the formation of wrinkles. Overexposure to the sun, especially when young, can not only lead to premature wrinkling but also significant DNA damage, potentially resulting in skin cancer, and the appearance of moles and freckles.
Sunburn and skin cancer are often a consequence of prolonged UV-B and UV-C radiation exposure. Wrinkling occurs due to the breakdown of the skin's structure, decreased production of collagen and elastin in the dermis, the weakening of underlying muscles, and the skin's diminished ability to retain moisture.
Protection from sun exposure, adequate hydration, and overall skin care are crucial to preventing wrinkles and maintaining skin health. Hence, the correct answer to what causes 90% of skin's wrinkles is a) Sun exposure.