Indicate which of these will not qualify as a marital deduction trust?

a. a trust that provides income to the surviving spouse for his life with a power for the spouse to allocate the trust principal among the decedent's children at the surviving spouse's death by provision in the surviving spouse's will, but passes all of the trust property to the decedent's children equally at the surviving spouse's death in the event she fails to exercise the power to allocate the trust among the children in her will.

b. a trust that provides all income to the surviving spouse for life with a power for the spouse to allocate the trust principal to her creditors.

c. a trust that provides the following: for all income to be paid to the surviving spouse at least annually; for the spouse to have the power to require the trustee to convert trust property to income-producing; that no one can appoint any trust property away from the spouse; that the spouse has the ability to allocate the trust property among the decedent's children; and the executor makes a QTIP election.

d. a trust that provides all income to the surviving spouse for life and requires that any trust assets at the time of the surviving spouses' death must be paid to the surviving spouse's estate.