In a Clinical Laboratory Without Gas Chromatography Instrumentation,the Common Method

In a clinical laboratory without gas chromatography instrumentation,the common method of choice used to measure ethanol in serum or plasma is a(n) :

A) enzymatic analysis using alcohol dehydrogenase and measurement of nicotinamide adenine dinucleotide (NADH) formation.
B) immunoassay using antibodies directed against acetaldehyde.
C) planar chromatography method combined with mass spectrometry.
D) potentiometric measurement of changes in voltage potential across electrodes.