Presuming the Year 2008 Is Involved,which,if Any,of the Following Disclaimers

Presuming the year 2008 is involved,which,if any,of the following disclaimers was wise from a tax standpoint?

A) Dylan, the only son, disclaims $500,000 of his $2,000,000 inheritance in favor of his mother, who receives $2,000,000.
B) Mona, the surviving spouse, disclaims $500,000 of her $2,000,000 in favor of the children, who receive only $1,500,000.
C) Andy, the surviving spouse, disclaims $500,000 of his $1,000,000 to the children, who receive $2,500,000.
D) Abigail, the surviving spouse, disclaims all of her $2,000,000 in favor of the Southern Baptist Convention (a qualified charity) .
E) None of the above.