Bonnie devised the residue of her estate in trust for the benefit of her husband, Otis. The relevant provisions of the trust read as follows:

"During my husband's lifetime, the Trustee shall distribute the net income of the trust to my husband on an annual or more frequent basis. In addition, the Trustee may distribute to my husband as much of the principal of the trust as the Trustee determines necessary for my husband's health, education, support in his accustomed manner of living, or maintenance. During my husband's lifetime, my husband shall have the power to appoint the trust principal to those of my children, upon such terms and conditions, as my husband shall direct in a signed writing delivered to the Trustee. Upon my husband's death, the trust property shall be distributed to my husband's estate if he so appoints by Will through a provision specifically referring to this power. In default thereof, the property shall be distributed to my then$-$living issue, per stirpes.

$($a$)$ Does Bonnie's devise of property to the trust qualify for the marital deduction?

$($b$)$ Does the result change if$,$ instead of requiring the Trustee to distribute the net income of the trust directly, the trust provided Otis with the annual right to withdraw trust income?

$($c$)$ Suppose the residue of Bonnie's estate consists primarily of undeveloped real property held for investment. Does this present an issue concerning qualification of the devise for the marital deduction?

$($d$)$ Suppose the trust instrument further provided that the Trustee possessed discretion to allocate receipts and disbursements between income and principal in order to fairly balance the respective interests of the income and remainder beneficiaries. Would this power jeopardize allowance of the marital deduction?

$($e$)$ Following Bonnie's death, Otis directs the Trustee to make a distribution to his and Bonnie's children. What are the tax consequences of the distribution to Otis?

$($f$)$ Suppose the trust instrument didn't permit Otis to appoint the trust principal to his probate estate by way of his will, Would the marital deduction still be available?