## **Core Concept**
The question tests understanding of anticoagulants used in blood glucose estimation and their role in preventing glycolysis. Glycolysis is the metabolic pathway that converts glucose into pyruvate, releasing energy. In the context of blood glucose measurement, preventing glycolysis is crucial to ensure accurate glucose levels.

## **Why the Correct Answer is Right**
The correct answer, , contains **sodium fluoride** (NaF), which is a glycolysis inhibitor. Sodium fluoride works by inhibiting the enzyme **enolase**, a key enzyme in the glycolytic pathway. By inhibiting enolase, sodium fluoride effectively prevents the consumption of glucose by cells in the blood sample, thereby providing an accurate measurement of blood glucose levels.

## **Why Each Wrong Option is Incorrect**
* **Option A:** - This option does not contain a known glycolysis inhibitor.
* **Option B:** - While is an anticoagulant, it does not contain a glycolysis inhibitor.
* **Option C:** - This option does not specifically prevent glycolysis.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **sodium fluoride** is commonly used in tubes for blood glucose measurement because it effectively inhibits glycolysis, ensuring that the glucose levels measured are as close to the actual in vivo levels as possible. This is particularly important in clinical settings where accurate glucose measurements are critical for diagnosis and management.

## **Correct Answer:** . Sodium fluoride.