What are the main types of fiber?

• A. Soluble and insoluble.
• B. Animal and plant
• C. Simple and complex
• D. Oats and barley

Answer: (D)

The main distinction for dietary fiber is how it behaves in water, giving two broad types: soluble fiber and insoluble fiber. Soluble fiber dissolves in water to form a gel-like substance, which can slow digestion, help lower cholesterol, and improve blood sugar control. Insoluble fiber does not dissolve and adds bulk to stool, helping to promote regular bowel movements and maintain gut health. Oats and barley are well-known sources of soluble fiber because they contain beta-glucans, but they illustrate the soluble-fiber category rather than define the classification itself. The other options mix up categories by origin (animal vs plant), carbohydrate structure (simple vs complex), or by naming specific foods rather than the fundamental fiber types.