19. A key intermediate in the formation of "ketone bodies" is(A)succinyl-CoA(B)methyl malonyl-CoA(C)propionyl-CoA(D)acetoacetyl-CoA

6. Which one of the following statements is true about catabolic pathways?(A)They combine molecules into more complex and energy-rich molecules.(B)They belong to the reduction reaction.(C)They are usually coupled with anabolic pathways and generate energy in the form of ATP.(D)They do not need enzyme catalysts.