The complete oxidation of one molecule of palmitic acid involves several steps, including beta-oxidation and the citric acid cycle (also known as the Krebs cycle). These processes generate ATP through oxidative phosphorylation.

1. Beta-oxidation:
- Palmitic acid is a saturated fatty acid with 16 carbon atoms. It undergoes a series of reactions known as beta-oxidation to generate acetyl-CoA molecules.
- Each round of beta-oxidation removes two carbon units, producing one molecule of acetyl-CoA, one molecule of NADH, and one molecule of FADH2.
- Since palmitic acid has 16 carbon atoms, it goes through 7 rounds of beta-oxidation, resulting in the production of 8 molecules of acetyl-CoA, 7 molecules of NADH, and 7 molecules of FADH2.

2. Citric acid cycle:
- Each molecule of acetyl-CoA enters the citric acid cycle, where it is completely oxidized.
- In the citric acid cycle, each acetyl-CoA molecule generates three molecules of NADH, one molecule of FADH2, and one molecule of GTP (which can be converted to ATP).

3. ATP production:
- Each molecule of NADH generated in both beta-oxidation and the citric acid cycle can produce 2.5 ATP through oxidative phosphorylation.
- Each molecule of FADH2 generated in both beta-oxidation and the citric acid cycle can produce 1.5 ATP through oxidative phosphorylation.
- Each molecule of GTP can be converted to ATP, resulting in the production of one ATP.

Calculating the total ATP production:
- 7 molecules of NADH from beta-oxidation = 7 x 2.5 ATP = 17.5 ATP
- 7 molecules of FADH2 from beta-oxidation = 7 x 1.5 ATP = 10.5 ATP
- 8 molecules of NADH from the citric acid cycle = 8 x 2.5 ATP = 20 ATP
- 8 molecules of FADH2 from the citric acid cycle = 8 x 1.5 ATP = 12 ATP
- 8 molecules of GTP from the citric acid cycle = 8 ATP

Total ATP production = 17.5 + 10.5 + 20 + 12 + 8 = 68 ATP

Therefore, the correct answer is option 'D' - 68 ATP.