Mrs$.$ Riley dies in $2023$ leaving her entire $$20$ million estate through her will to her penniless husband, John. His estate goes to their children at his death. He has terminal cancer with a life expectancy of only $1$ to $2$ years. The alternative valuation date value of Mrs$.$ Rileys entire estate is equal to $$18,000,000.$ Select the post mortem technique John should utilize to reduce the overall estate tax liability of both estates:A$.$Elect Portability.B$.$Elect to use the alternative valuation date.C$.$Disclaim $$2,000,000$ and elect to use the alternative valuation date.D$.$Do Nothing.