The citric acid cycle produces 3 NADH.

Each FADH$_2$ produced in the citric acid cycle and glycolysis is converted into 2 NADH. Therefore, each FADH$_2$ produced is equivalent to 2 NADH. The citric acid cycle produces 2 FADH$_2$, equivalent to 4 NADH, while glycolysis produces 2 FADH$_2$, equivalent to 4 NADH.

The total NADH produced by:

Glycolysis: 2 NADH + 4 (FADH$_2$) = 2 + 4 =6 NADH

Citric Acid Cycle: 3 NADH + 4 (FADH$_2$) = 3 + 4 = 7 NADH

Therefore, the citric acid cycle produces the most NADH.