Final answer:
The senescent behavior of normal cells is associated with loss of telomerase activity.
Step-by-step explanation:
The senescent behavior of normal cells is associated with D. loss of telomerase activity. Telomerase is an enzyme that helps maintain the length of telomeres, the protective caps at the ends of chromosomes.
As cells age, telomerase activity decreases, leading to shortened telomeres and senescence. This loss of telomerase activity is a characteristic feature of normal cell aging.