Carbohydrate metabolism is controlled by

Options

A. parathormone
B. insulin
C. glucose
D. vitamin `B_(12)`

Answer

**Step-by-Step Solution:**

1. **Understanding Carbohydrate Metabolism**: Carbohydrate metabolism refers to the biochemical processes that break down carbohydrates to produce energy. This includes glycolysis, gluconeogenesis, and the citric acid cycle.

2. **Identifying Hormones Involved**: Several hormones regulate carbohydrate metabolism. The key hormones include insulin, glucagon, epinephrine, and cortisol. Each of these hormones plays a distinct role in managing blood glucose levels.

3. **Evaluating the Options**:
- **Parathormone**: This hormone is secreted by the parathyroid gland and primarily regulates calcium levels in the blood, not carbohydrates.
- **Vitamin B12**: This vitamin is essential for red blood cell formation and neurological function but does not directly influence carbohydrate metabolism.
- **Insulin**: This hormone is secreted by the beta cells of the pancreas and is crucial for lowering blood glucose levels by facilitating the uptake of glucose into cells and promoting glycogen storage in the liver and muscles.

4. **Conclusion**: Based on the roles of the hormones discussed, insulin is the primary hormone that controls carbohydrate metabolism by regulating blood glucose levels.

5. **Final Answer**: Therefore, the correct answer is **insulin**.

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