What Contract Price Do I Use for the Rental Asset "Cost?"

I'm starting to fillin the Capital Gains Tax data in TT and I don't know what price to use from the contract.  The choises are: Contract Sales price, Gross Amount Due From Borrower, Gross Amount Due to Seller, Total Paid by/For Borrower or Total Reduction Amount Due Seller?  

 

Thanks,

 

Kenneth Sibert