Which one of the following is a wrong matching of a microbe and its industrial product?

The wrong matching is Clostridium butylicum - Lactic acid.

Monascus purpureus is a fungus used in the production of statins, which are cholesterol-lowering drugs.
Aspergillus niger is a fungus used in the production of citric acid.
Acetobacter aceti is a bacterium used in the production of acetic acid (vinegar).
Clostridium butylicum is a bacterium used in the production of butyric acid, not lactic acid. Lactic acid is produced by bacteria like Lactobacillus.
Therefore, the correct answer is Clostridium butylicum - Lactic acid.