Negotiation as a Means of Resolving Conflict Doesn't Work as Often

Negotiation as a means of resolving conflict doesn't work as often as it might because in most conflicts

A) adversaries tend to overlook the possibility of both parties achieving a favourable outcome.
B) adversaries refuse to involve objective mediators.
C) one party has more power than the other.
D) adversaries tend to overestimate the amount of trust they should have for one another.
E) adversaries refuse to communicate with one another.