During degradation of odd-chain fatty acids, the final round of π≤π≤-oxidation occurs on a 5-carbon chain (instead of the 4-carbon chain in the last round for even-chain fatty acids), producing 1 acetylCoA and 1 _____-carbon-based-CoA. What is the missing number?
1) 2
2) 3
3) 4
4) 5
