The primary difference between distributive bargaining and interest-based bargaining is that:
Distributive bargaining is a type of negotiation.
This statement correctly identifies distributive bargaining as a negotiation approach, predominantly characterized by a competitive or adversarial nature, where parties aim to divide a fixed resource (like money). In contrast, interest-based bargaining focuses on collaborative problem-solving to achieve mutually beneficial outcomes for all parties involved.
So, the best choice related to the primary difference in the context you are examining would be the first response:
Distributive bargaining is a type of negotiation.