What are the reasons for utilizing a bypass trust after ATRA?

(A) Sheltering appreciation between the first and second deaths.

(B) Protection from creditors of the surviving spouse.

(C) Preserving deceased spouses GST exemption amount.

(D) Protecting children from prior marriage of first spouse to die.

(E) All of the above.

Can you provide a detailed explanation for your answer? Please only answer if you have a strong background in estate planning.