Which of the following conditions is considered a secondary aging illness?

Parkinson's disease is classified as a secondary aging illness because it is a neurodegenerative disorder that specifically results from a combination of genetic and environmental factors, rather than being a natural part of the aging process itself. While aging can increase the risk of developing such conditions, secondary aging refers to those diseases or conditions that arise from lifestyle choices, environmental impacts, or specific health events, rather than the typical biological aging processes.

Normal cognitive decline, childhood obesity, and a temporary stress response, on the other hand, reflect different concepts within the framework of aging. Normal cognitive decline is seen as an expected part of aging that affects many individuals as they get older, making it a primary aging characteristic. Childhood obesity is a condition influenced by various factors such as diet and lifestyle, but it does not directly relate to the aging process of an adult. Meanwhile, a temporary stress response is a physiological reaction that occurs in response to different stressors and is not directly linked to aging itself. Thus, while these other options relate to health and development, they do not fit the definition of secondary aging illnesses as aptly as Parkinson's disease does.