Final answer:
The process of aging is more likely to lead to a decreased absorption of fat-soluble vitamins due to changes in the digestive system and decreased function of digestive organs.
Step-by-step explanation:
The process of aging affects various organs and bodily functions, and within the context of the digestive system, it typically leads to a decline in efficiency rather than an increase. Option b, decreased absorption of fat-soluble vitamins, is a result of age-related changes that can include reduced bile production and changes in the intestinal lining, which impair the ability to absorb these vitamins. Increased enzyme activity and liver mass typically do not occur with aging, making options a and c less likely. As we age, changes in the digestive system can include constipation, decreased appetite, decreased strength, and tone of muscular tissue of the digestive tract, and reduced efficiency of accessory digestive organs like the pancreas, which can lead to issues such as constricted pancreatic ducts, as indicated in option d.