**Core Concept**
Aldolase is a type of enzyme that plays a crucial role in glycolysis, specifically in the conversion of fructose-1,6-bisphosphate into glyceraldehyde-3-phosphate and dihydroxyacetone phosphate. This enzyme catalyzes the cleavage of a carbon-carbon bond, resulting in the formation of two new molecules.

**Why the Correct Answer is Right**
Aldolase acts by facilitating the transfer of electrons and the formation of new covalent bonds. The enzyme's active site contains a divalent cation, typically zinc or magnesium, which helps to stabilize the transition state and facilitate the reaction. Aldolase is specific to its substrate, fructose-1,6-bisphosphate, and requires the presence of a divalent cation to function.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because aldolase does not act on glucose-6-phosphate, which is instead converted by the enzyme hexokinase or glucokinase.
**Option B:** This option is incorrect because aldolase is not involved in the conversion of pyruvate to lactate, which is instead catalyzed by the enzyme lactate dehydrogenase.
**Option C:** This option is incorrect because aldolase does not act on glyceraldehyde-3-phosphate, which is instead converted by the enzyme triosephosphate isomerase.

**Clinical Pearl / High-Yield Fact**
Aldolase is often elevated in the serum of patients with muscle damage or rhabdomyolysis, making it a useful marker for diagnosing muscle injury.

**Correct Answer:** D. Fructose-1,6-bisphosphate.