Final answer:
People with longevity genes tend to live longer, possess a stronger immune system, and have an enhanced defense against diseases, often attributed to the production of more robust immune cells and the effective use of nutrients, potentially aided by a healthy lifestyle. The correct option is D.
Step-by-step explanation:
People who have longevity genes are typically associated with an increased likelihood of living past the age of 90 (long lifespans), having a bolstered immune system, and possessing a greater ability to defend against diseases. These genes allow for a more robust response to pathogens and a slower progression of immunosenescence, which is the gradual deterioration of the immune system associated with aging.
For example, the process of thymic involution, a major factor in age-related immune deficiency, may be less pronounced in individuals with certain genetic profiles, therefore contributing to a healthier and longer life. These people may also have cells that are produced in higher numbers and can utilize nutrients more effectively, adding to their longevity.
Moreover, adopting a healthy lifestyle that includes a balanced diet and regular physical and mental exercise can augment the benefits provided by longevity genes, potentially increasing one's chances of staying healthy well into advanced age.