In the paper by Muoio et al, they describe a role for Carnitine Acetyltransferase (CrAT) in metabolic flexibility. Explain how CrAT enables flexible substrate switching in mitochondria.

A. CrAT enhances mitochondrial biogenesis, increasing substrate availability.
B. CrAT transports acetyl groups across the mitochondrial membrane, facilitating metabolic flexibility.
C. CrAT inhibits glycolysis, promoting reliance on fatty acids as substrates.
D. CrAT increases ATP production, enabling the switch between aerobic and anaerobic metabolism.