Ultimate aim for negotiation is to reach an agreement which avoids use of force and bring a peaceful solution to the problem. Once a successful mediated negotiation is finalized, the next step is to officialize the agreed conditions through a diplomatic agreement of which clauses would be binding for all signatory parties. A diplomatic agreement or protocol, in this context, is a binding legal text produced through negotiations between disputing parties to institutionalize the conditions agreed. Therefore, the correct option is D.