What is a condition precedent?

Question $25$ options:

an undertaking, conditional on the execution of a contract between the parties, that a promisee makes to a promisor prior to entering into a contract

an event that happens before a contract takes effect

an unconditional undertaking given by a promisee to the promisor to perform an event before a contract takes effect

any set of circumstances or events that the parties agree must be satisfied or must happen before their contract takes effect