Barney and Betty have been married for 45 years and have amassed a fortune of $27 million dollars. Barney's estate consists of $12 million in probate assets, while Betty's estate consists of $15 million in probate assets. Barney was recently diagnosed with inoperable cancer but Betty remains in good health. Barney's Will provides for the funding of a credit shelter by-pass trust equal to the applicable exemption amount, with any remainder passing to Betty via the marital deduction. Barney and Betty have not made any adjusted taxable gifts during life. Assuming coverage can be obtained, which type of policy will provide them with appropriate liquidity to pay estate taxes regardless of who dies first?

1) Whole life 2) A second-to-die policy 3) A viatical settlement 4) No insurance is needed; their combined estates will not be subject to federal estate taxes