A hires B to work on a construction project including his scuba diving in order to build an underwater museum off of a tourist resort's shore. The project is in the Arctic and is a very dangerous job. A has signed a contract that says that $B$ will not sue $A$ in the event of injuries that happen on the job, whether the fault of natural forces, or of any of the other crew, even if there is gross negligence on the expedition. This contract, which is probably illegal, is:

an exculpatory agreement

an unconscionable contract

a non$-$voidable contract

detrimental reliance contract

none of the other choices; the contract is legal