Don Slips and Falls on a Patch of Ice on Ella's

Don slips and falls on a patch of ice on Ella's property. Ella offers Don $10,000 if he promises not to pursue any slip-and-fall legal claim against her. Don agrees, but later discovers that it will cost $40,000 in medical expenses for a latent injury. In Don's suit against Ella, Don will most likely recover

A) $30,000 to pay the costs over what Ella already paid Don.
B) nothing.
C) the estimated amount to pay the costs and any other liability.
D) the exact amount to pay the costs and no more.