In which of the following situations would part of the value of Bill's vacation home (other than any unconsumed payments received and related interest earned prior to his death) be included in Bill's gross estate upon his death?

A) Bill accepts a self-canceling installment note for the sale of his vacation home to his son, and Bill dies during the term of the note.

B) Bill gives his vacation home to his son using a qualified personal residence trust (QPRT) in which Bill retains the right to live in the house for 15 years, and Bill dies after 20 years.

C) Bill makes a regular installment sale of his vacation home to his son, and Bill dies during the term of the installment note.

D) Bill sells his vacation home to his son in exchange for a private annuity, and Bill dies 4 years later.