In Killian v.Ricchetti,the case in the text,the agreement between the parties is an example of a:

A) concurrent condition.
B) constructive condition.
C) condition subsequent.
D) condition precedent.

Condition Precedent

A contractual requirement that must be fulfilled before a party's obligation or right comes into effect.

Constructive Condition

A condition presumed by law to exist in a contract, even if not explicitly mentioned, to ensure fairness and fulfill the intention of the parties.

Concurrent Condition

In contract law, these are conditions that must occur or be performed at the same time by both parties involved in a contract.