During strenuous exercise, the NADH formed in the glyceraldehyde 3-phosphate dehydrogenase reaction in skeletal muscle must be reoxidized to NAD+ if glycolysis is to continue. The most important reaction involved in the reoxidation of NADH is:.
a) dihydroxyacetone phosphate ⇌ glycerol 3-phosphate.
b) glucose 6-phosphate ⇌ fructose 6-phosphate.
c) isocitrate ⇌ α-ketoglutarate.
d) oxaloacetate ⇌ malate.
e) pyruvate ⇌ lactate.

Answer is option "e"

Explanation:

The decrease of pyruvate to lactate, catalyzed by lactate dehydrogenase (LDH; Pyruvate + NADH + H+ ⇌ Lactate + NAD+) in the cytosol of various cells, has been seen as a metabolic "stalemate", or possibly more properly, a metabolic round about drive since lactate can simply rejoin the metabolic framework by methods for pyruvate. In warm-blooded creatures, the LDH response is additionally viewed as "close harmony", implying that the response is managed primarily by the convergences of its reactants and items, as opposed to by increasingly advanced methods for an allosteric guideline or covalent adjustment. Since the balance for the LDH response lies far to one side, paying little mind to LDH isoform, the suggestion may be that LDH once in a while favors the turn around response (i.e., lactate oxidation) in vivo. SO, the right answer is option e " pyruvate⇌lactate.