A contractor and owner sign a contract, then later sign a separate written agreement that clearly changes the completion date and adds $6,000 in scope. This later signed agreement is best described as:

Explanation

A later writing signed by both parties that moves the completion date and adds $6,000 of scope is a modification of the existing contract, supported by fresh consideration on both sides — new work for new money (Civil Code §1698(a)). (d) is the usual error on this item: the parol evidence rule (Code Civ. Proc. §1856) excludes PRIOR or contemporaneous agreements that would contradict an integrated writing; it says nothing about an agreement made afterwards. (c) reaches for novation, which under Civil Code §1530 requires the parties to intend to extinguish the old obligation and substitute a new one; adding scope leaves the original contract standing. (b) calls a signed writing oral.