Final answer:
The feature not part of Carneiro's model for early state formation is long-distance trade. His model includes social and geographic circumscription, war, and competition, which contribute to the centralization of power and the emergence of states.
Step-by-step explanation:
The feature that is not part of Carneiro's model for early state formation is A. long-distance trade. Carneiro's theory of state formation focuses primarily on environmental and societal constraints that lead to the emergence of a state. The core concepts included in his model are social circumscription, war, geographic circumscription, and competition among groups. Social and geographic circumscription limit the movement of people which, combined with population pressure, can lead to increased conflicts and competition for resources, ultimately catalyzing the establishment of more centralized leadership or a state.
The integrative and conflict pressures that stimulate state formation include factors such as population growth, social stratification, regional trade, and militaristic threats. These collectively contribute to the centralization of power within societies evolving from chiefdoms to states.