What is a key characteristic of a bilateral contract?

A key characteristic of a bilateral contract is that it involves a mutual agreement where both parties have an obligation to fulfill their respective promises. This means that each party's commitment is contingent upon the other fulfilling their part of the agreement. For instance, in a typical scenario such as the sale of a house, the seller agrees to transfer the property in exchange for payment from the buyer. Here, both the buyer and the seller are bound to perform their duties – one to pay and the other to provide the property.

The other options do not accurately capture the essence of bilateral contracts. The requirement that only one party must perform describes a unilateral contract, where only one party has an obligation. Verbal agreements can be part of contracts but are not exclusive to bilateral contracts; written contracts can also be bilateral. Lastly, equal financial contributions are not a necessity in a bilateral contract, as the agreement can be structured in various ways without the requirement for both parties to contribute equally.