Kali enters into an agreement with Leon where Leon agrees to buy Kali's car next Friday for $$5,000$ cash. The agreement will be fully discharged when Kali and Leon:

a$)$ exchange the car for the cash.

b$)$ shake hands and leave.

c$)$ sign an agreement documentinfor the transaction.

d$)$ when Kali has the car inspected to Leon's satisfaction.