15. On January l of year 1, D died leaving property in trust, income to A for A's life, remainder to B or B's estate. A died on January l of year 2. On July 1 of year 2 B disclaimed a one-half interest in the property in a manner comporting with the Code's writing and notice requirements. What are the tax consequences of B's attempted disclaimer? Explain answer

A. The disclaimer is valid. B. The disclaimer is invalid as untimely. C. The disclaimer is invalid because it is a disclaimer of a partial interest. D. The disclaimer is invalid as untimely and as a disclaimer of a partial interest.