**Core Concept**
Glycolysis is a crucial metabolic pathway that converts glucose into pyruvate, generating energy for the cell. Inhibiting key enzymes in this pathway can disrupt glycolytic flux. Fluoride ions (F-) are known to interfere with certain glycolytic enzymes, specifically targeting those involved in the phosphoglycerate kinase and pyruvate kinase reactions.

**Why the Correct Answer is Right**
Fluoride ions inhibit the enzyme enolase, which catalyzes the conversion of 2-phosphoglycerate (2-PG) to phosphoenolpyruvate (PEP) in the glycolytic pathway. This step is critical for the regeneration of the high-energy phosphate bond in PEP, which is then used to drive the subsequent conversion of PEP to pyruvate. By inhibiting enolase, fluoride reduces the availability of PEP, thereby slowing down glycolytic flux. The inhibition of enolase by fluoride is thought to occur due to its ability to bind to the magnesium ion (Mg2+) cofactor required for enolase activity.

**Why Each Wrong Option is Incorrect**
**Option A:** Hexokinase is an enzyme involved in the first committed step of glycolysis, where glucose is converted to glucose-6-phosphate. Fluoride does not inhibit hexokinase directly.
**Option B:** Aldolase is an enzyme responsible for the conversion of fructose-1,6-bisphosphate to glyceraldehyde-3-phosphate and dihydroxyacetone phosphate in glycolysis. Fluoride does not inhibit aldolase.
**Option D:** Pyruvate kinase is an enzyme that catalyzes the final step of glycolysis, where phosphoenolpyruvate is converted to pyruvate. Although fluoride can indirectly affect pyruvate kinase activity by reducing the availability of PEP, it does not directly inhibit pyruvate kinase.

**Clinical Pearl / High-Yield Fact**
Fluoride is a well-known inhibitor of enolase, which can be exploited in the laboratory to measure enolase activity. This knowledge can be applied in clinical settings to diagnose and manage conditions related to glycolytic enzyme deficiencies.

**✓ Correct Answer: C. Enolase**