Final answer:
Carnitine palmitoyltransferase I is involved in the beta-oxidation pathway, assisting in the transport of fatty acids into the mitochondria for their breakdown into acetyl CoA, which then enters the Krebs cycle to generate ATP.
Step-by-step explanation:
Carnitine palmitoyltransferase I (CPTI) is an enzyme that plays a critical role in the transport of fatty acids from the cytosol into the mitochondria for their subsequent breakdown through β-oxidation. This process begins in the cytoplasm, where fatty acids are converted to fatty acyl CoA molecules. These fatty acyl CoA molecules combine with carnitine to form fatty acyl carnitine, which can then cross the mitochondrial membrane. Once inside the mitochondrial matrix, the fatty acyl carnitine is converted back to fatty acyl CoA, then to acetyl CoA, which enters the Krebs cycle to produce ATP. Therefore, the correct answer is d) Beta-oxidation.