Correct answer: D. Collectivization
Explanation: The direct answer is D: Collectivization. Under Joseph Stalin, Soviet agriculture was reorganized into collective farms, in which land, animals, and equipment were brought under collective or state-directed control. The policy aimed to increase state control over grain and support rapid industrialization, although it caused severe disruption, resistance, shortages, and famine in several areas. The reasoning is: the question asks for Stalin's agricultural policy; the distinctive policy was collectivization; therefore D is correct. Option A, free trade, means allowing exchange with limited state restriction and was not the defining agricultural policy under Stalin. Option B, private feudalism, is not the name of the Soviet policy and conflicts with communist efforts to end private landlord control. Option C, maritime expansion, concerns naval or overseas growth, not farming organization. Option D correctly identifies the compulsory collectivization programme. It is useful to connect it with Stalin's Five-Year Plans, but do not assume that every result was successful or peaceful. Memory cue: Stalin plus agriculture = collective farms.