Final answer:
Whole wheat bread (d) is the best source of insoluble fiber among the options provided. Insoluble fiber adds bulk to the stool and aids in preventing constipation and hemorrhoids. Other good sources include wheat bran, beans, potatoes, and various vegetables.
Step-by-step explanation:
The medical assistant (MA) is correct to suggest increasing the intake of insoluble fiber as it helps to prevent constipation by adding bulk to the stool and promoting peristalsis in the digestive tract. Among the options provided, the best source of insoluble fiber would be d) Whole wheat bread. This is because whole wheat bread includes whole wheat, which is a good source of insoluble fiber, helpful for the noted conditions.
Other foods high in insoluble fiber include wheat bran, beans, potatoes, cabbage, bell peppers, grapes, sweet potatoes, and the skins of root vegetables. While foods like apples also contain fiber, they are particularly known for their soluble fiber content, which forms a gel-like substance in the intestines but is not the type of fiber primarily responsible for preventing constipation and hemorrhoids.