Question

david is 50 - years old. he has a lot of aches and pains in his joints and muscles that he had not experienced in the past. he doesnt feel as physically strong as he used to. he is also not as flexible anymore. dave used to be very active and do a lot of sports, including running 2 miles a day. this best demonstrates which theory of aging?
o cellular theory
o telomere theory
o free - radical theory
o wear - and - tear theory

Explanation:

• Cellular theory: Focuses on cell - related mechanisms like cell senescence and apoptosis. But the description here is more about physical wear rather than cellular - level processes.
• Telomere theory: Deals with the shortening of telomeres (end - caps of chromosomes) over time. There is no mention of genetic or chromosomal aspects in the given description.
• Free - radical theory: Relates to damage caused by free radicals (unstable molecules). The problem description does not mention oxidative stress or free - radical damage.
• Wear - and - tear theory: Suggests that the body's systems and organs wear out over time due to use. David's joint and muscle aches, loss of strength and flexibility (which can be seen as a form of 'wear' from his previous active lifestyle) fit this theory.

Answer:

wear - and - tear theory