What causes deep wrinkles in the skin?

Deep wrinkles in the skin are primarily caused by changes in the structure of collagen fibers. Collagen specifically provides support and elasticity to the skin, and as we age or experience various environmental factors, the integrity of collagen can deteriorate. This structural alteration leads to a loss of firmness and elasticity, contributing to the development of deep wrinkles.

While decreased blood supply and excessive sun exposure also influence skin quality, they do so in different ways. Decreased blood supply can result in a less vibrant appearance and may contribute to skin aging but is not the direct cause of deep wrinkles. Increased oil production typically affects the skin's surface texture and moisture levels but does not cause deep wrinkles. Thus, the direct relationship between the structural changes in collagen and the formation of deep wrinkles makes the first option the most accurate answer.