Pyruvate Is the End- Product of Glycolysis

Pyruvate is the end- product of glycolysis. Many organisms, such as anaerobic bacteria, can only produce energy by glycolysis; therefore, pyruvate has no more potential for ATP generation for these organisms. Rather than simply excrete pyruvate, this molecule is changed to another molecule such as lactate. In these organisms, why is pyruvate changed to lactate and excreted, rather than simply excreted?

A) Pyruvate export requires more energy than lactate.
B) Electrons (and protons) are added to pyruvate to make lactate.
C) NAD+ is regenerated as pyruvate is changed to lactate.
D) Substrate level phosphorylation changes pyruvate to lactate.
E) both B and C