Answer:d. They have a unilateral contract.
Step-by-step explanation:
A unilateral contract is a contract that is only valid upon performance, which means one has to complete a particular action for it to be valid. The person offering this contact will promise the person who has to perform the act that upon the completion of that act they will pay them. When the other party has finished that action than the offer becomes valid from then. Uni- refers to the fact that the agreement or promise has been made bay a single person.
In this case above Tanner promised Skyler that if he drives his car to New Orleans he will pay him $200 , indeed Skylar drove the car to New Orleans which means he completed the requested action and that makes up a Unilateral Contract and Tanner has to pay Skyler .