Negotiation between labor and management is called what? mediation, collective bargaining, lockout,

Negotiation between labor and management is called COLLECTIVE BARGAINING.
Collective bargaining refers to the process of negotiating terms of employment between employers and employees. The terms negotiated usually include: amount of salary to be paid, working conditions, over time, shift length, etc. The results obtained through collective bargaining is called collective bargaining agreement and it establishes the rules of employment for a period of time. 

The third answer is correct.