Final answer:
Experiments have demonstrated that telomerase is involved in cellular aging, as it adds sequences to the ends of chromosomes to prevent telomere shortening, a key factor in aging.
Step-by-step explanation:
Experiments have shown that telomerase is involved in cellular aging. Telomerase is an enzyme that adds DNA sequence repeats to the ends of chromosomes, known as telomeres, to prevent them from shortening with every cell division. Without sufficient telomerase activity, telomeres become progressively shorter as cells divide, leading to cellular aging and the potential onset of age-related diseases.
Cells that undergo cell division with each cycle experience telomere shortening because most somatic cells do not produce adequate levels of telomerase. This gradual shortening of telomeres is associated with cellular aging, and the reactivation of telomerase has been shown to reverse signs of aging in telomerase-deficient mice by extending telomeres, reducing DNA damage, and improving the function of various organs.
Therefore, the correct answer to the multiple-choice question is A. cellular aging.