Answer:
4 ATP molecules
Explanation:
Normally, about 11 ATP molecules are generated as the result of Beta-Oxidation of saturated fatty acid in Kreb's Cycle. But the total removal of acetyl-CoA under certain aerobic condition decreases the overall yield and approximately 4 ATP molecules comes out from each removal of acetyl-CoA.
I believe rottening would be the answer. Rotting, dead plants and animal feaces make great fertilizers.