Regarding the Krebs cycle, indicate which processes are true (choose more than one answer):

a- Acetyl-CoA and oxaloacetate form acetoglutarate.
b- The cycle works in the presence of oxygen
c- It is a direct source of ATP
d- The carbons of CO2 removed in the cycle come from the acetyl group of acetyl-CoA.
e- The cycle contains metabolites that correspond to amphibole and anabolic pathways.