Which of the Following Procedures Carried Out Will Reduce Both

Which of the following procedures carried out will reduce both Mary's future gross estate and her probate estate?

A) Mary issues a timely disclaimer as to real estate that is willed to her by her grandfather.
B) Mary creates a revocable trust naming her children as the beneficiaries.
C) One year before her death, Mary gives an insurance policy on her life to her son, the designated beneficiary.
D) Mary purchases real estate as joint tenants with her sister. Mary predeceases her sister.
E) None of the above.