Final answer:
In integrative negotiation, it's not necessary for each party to be equally responsible for the other's needs and outcomes; the primary aim is a mutually beneficial solution.
Step-by-step explanation:
The question asks which of the following is not necessary for integrative negotiation to succeed. The options provided suggest different aspects that are typically important for a successful integrative negotiation, such as mutual interest in outcomes, commitment to a mutually beneficial goal, congenial interpersonal styles, and the explicit expression of needs and recognition of differences. However, integrative negotiation doesn't require that each party assume responsibility for the other's needs and outcomes to the same extent as their own. The goal is to reach a mutually beneficial outcome, but this does not necessarily mean each party must be equally invested in the other's needs.