Final answer:
Rapidly developing cells in adulthood are typically found in the skin, digestive tract, and epithelial cells, corresponding to answer C: Liver; respiratory; epithelial.
Step-by-step explanation:
During adulthood, you would find rapidly developing cells in the skin, the digestive tract, and most epithelial cells. Thus, the correct answer is C: Liver; respiratory; epithelial.
Cellular development in adults occurs primarily in regions of frequent wear and tear or those requiring constant renewal. For example, skin cells are constantly being shed and replaced due to external exposure. Similarly, the lining of the digestive tract undergoes rapid turnover to maintain its integrity against the abrasive effects of food and gastric acids. Epithelial cells, which can be found lining many organs and structures throughout the body, also exhibit rapid cell division to replace those that are old or damaged.