What is the definition of collective bargaining?

ongoing salary negotiations between an employee and a factory owner

an agreement among a group of factory owners to raise worker wages

a written set of guidelines about legal and illegal workplace conditions

labor union and employer negotiations about wages and other issues

The question is asking about the definition of collective bargaining. The bargaining in question is between the employer and the employees and the "collective" part refers to the fact that the employees all come together and argue their case as one entity - therefore, the correct answer is labor union and employer negotiations about wages and other issues"

labor union and employer negotiations about wages and other issues