Bargaining impasse occurs when: A. either party to negotiations violates the NLRA.

B. bargaining partners fail to agree on mutually acceptable terms of employment.

C. bargaining partners engage in concession bargaining.

D. a new contract is not agreed upon before the old contract expires.

Answer:B. bargaining partners fails to agree on mutual acceptable terms of employment.

Explanation:

This non agreement of mutually acceptable terms will prevent the performance of the contract. It's not limited to employment contracts but all types of contracts between two or more parties, the non agreement is usually settled by a third party by brokering or imposing conditions on the affected parties.