A contract in which both parties exchange promises is a:

A) voidable contract.
B) bilateral contract.
C) unilateral contract.
D) quasi contract.

A bilateral contract is a type of contract in which both parties exchange promises to do something in the future. This is in contrast to a unilateral contract, where only one party makes a promise, and a quasi-contract, which is not a true contract but rather a legal fiction used to prevent one party from being unjustly enriched by another. A voidable contract is a contract that can be legally avoided or cancelled by one of the parties, typically due to some sort of defect or problem with the formation of the contract.