Cathy's father passed away this year. He lef her the following assets: $$50,000$ of income in respect of a decedent $($IRD$).$ a $$164\mathrm{.}000$ payout from a life insurance policy $($that is not a modifed endowment contract$),$ and a $$100000$ inheritance $($consisting of qualified small business stock$)$ Which income item should be included in Cathy's gross income?

a$.$ The $S50,000$ of IRD

b$.$ The $$164000$ of life insurance proceeds.

c$.$ The $$100\mathrm{.}000$ inheritance $($of qualified small business stock$)$

d$.$ All of the above.