Final answer:
Celery is the best source of insoluble fiber among the options given, essential for aiding digestion and preventing constipation and hemorrhoids.
Step-by-step explanation:
If a medical assistant is encouraging a patient to increase her intake of insoluble fiber to help prevent constipation and hemorrhoids, among the options provided, d) Celery would be the best source of insoluble fiber. While all the options listed include dietary fiber, celery contains a higher proportion of insoluble fiber, which is essential for adding bulk to the stool and aiding in its passage through the digestive system.
Insoluble fiber does not dissolve in water and its benefits include increasing fecal bulk and preventing constipation. Foods such as whole wheat, wheat bran, and potatoes are high in insoluble fiber. Other good sources of insoluble fiber include root tubers and root vegetables, cabbage, bell peppers, grapes, and the skins of fruits and vegetables like sweet potatoes and onions.
It is important to note that while oats, apples, and lentils are good sources of fiber, they are particularly recognized for their soluble fiber content, which dissolves in water to form a gel-like substance in the gut, as opposed to the bulking quality of insoluble fiber. Therefore, for the specific goal of preventing constipation and hemorrhoids, celery is the food among the options given that is most associated with insoluble fiber.