Which of the Following Statements Is True of the Diels-Alder

Multiple Choice

Which of the following statements is true of the Diels-Alder reaction?

A) When the diene is electron-rich,the reaction works best when the dienophile contains one or more electron-withdrawing groups conjugated to its C C.
B) Substituents which are cis in the dienophile remain cis in the product.
C) Dienes which cannot achieve an s-cis conformation do not react in Diels-Alder reactions.
D) Secondary orbital interactions typically cause the endo product to be favored kinetically over the exo.
E) all of the above