Answer:
d. ratification
Explanation:
Ratification refers to making a contract legal through the consent. Basically when Jake agrees to accept the scooter and pay the contract price, as negotiated by the Cheryl.
Even though Cheryl has acted as an agent of Jake in front of the seller of scooter, even when Jake had not made any contract making that agent relationship valid.
This clearly embarks that the only way in which this contract can be validated is through ratification by Jake.