50. Which of the following is (are) true of the oxidation of 1 mol of palmitate (a 16-carbon saturated fatty acid； 16:0) by the β-oxidation pathway, beginning with the free fatty acid in the cytoplasm?
①Activation of the free fatty acid requires the equivalent of two ATPs.
② Inorganic pyrophosphate (PPi) is produced.
③Carnitine functions as an electron acceptor.
④8 mol of FADH2 are formed.
⑤8 mol of acetyl-CoA are formed.
⑥There is no direct involvement of NAD+.
(A)①and⑤ 
(B) ①②and⑤
(C) ①② and⑥ 
(D) ①③ and ⑤ 
(E)④ and⑤