True about dietary fibera) Soluble fiber ↑ metabolism of sugar in GITb) ↑bulk of stoolc) Only soluble fibers are included in dietd) ↑GI transit timee) Not prevention against colonic cancer

**Core Concept**
Dietary fiber, particularly soluble and insoluble types, plays a crucial role in maintaining gastrointestinal health. Soluble fiber dissolves in water, forming a gel-like substance that helps regulate bowel movements, while insoluble fiber acts as a bulking agent, adding bulk to stool.

**Why the Correct Answer is Right**
Soluble fiber increases the metabolism of sugar in the gastrointestinal tract (GIT) by delaying gastric emptying, which in turn slows down the absorption of glucose. This helps regulate blood sugar levels. Soluble fiber also increases the bulk of stool, making it easier to pass, and helps prevent constipation. Additionally, both soluble and insoluble fibers can increase GI transit time, which helps prevent diarrhea and other gastrointestinal disorders.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because only soluble fiber increases the metabolism of sugar in the GIT, not insoluble fiber. Insoluble fiber primarily acts as a bulking agent.
**Option C:** Incorrect because both soluble and insoluble fibers are included in the diet, not just soluble fibers. Soluble fibers include pectin, gum, and beta-glucans, while insoluble fibers include cellulose, hemicellulose, and lignin.
**Option E:** Incorrect because fiber, particularly soluble fiber, can help prevent colon cancer by reducing the absorption of bile acids and increasing the production of short-chain fatty acids, which have anti-carcinogenic properties.

**Clinical Pearl / High-Yield Fact**
A high-fiber diet can help regulate blood sugar levels, promote regular bowel movements, and reduce the risk of colon cancer.

**Correct Answer: B. ↑ bulk of stool.**