When does primary aging typically begin to affect an individual?

Primary aging, which refers to the biological process of aging that occurs naturally over time, typically begins to have noticeable effects during late adulthood. This period usually marks the beginning of significant physiological changes, such as decreased muscle strength, slower metabolism, and various bodily functions becoming less efficient.

Late adulthood generally spans from around ages 65 and onward, where individuals often experience more pronounced aging signs, including changes in skin elasticity, cognitive processing speed, and susceptibility to age-related health issues. While some aspects of aging can start to be seen in middle adulthood, primary aging effects are more prevalent and recognizable in late adulthood, making this the correct answer.