Johnny purchases a house, doesn't want furniture left behind. He signs Tuesday, changes mind Thursday, calls agent to add furniture to contract. What is this?

An option is incorrect because it refers to the right to purchase or lease property at a specified price within a set period, not a modification to an existing contract. Options are typically negotiated before contract execution, not added afterward.

A novation is incorrect because it involves replacing one party to a contract with a new party, with the consent of all involved. This scenario doesn't involve substituting parties but rather adding terms to the existing agreement.

An amendment is incorrect because while similar to an addendum, an amendment typically modifies existing terms rather than adding entirely new ones. Adding furniture requirements represents adding new terms, not modifying existing ones.