Question

Use the map below to answer the following question. The area highlighted in red is Kaliningrad.

Map of the Soviet Union is highlighted in beige. Kaliningrad lies to the west of beige shaded area, is surrounded mostly by land, and is highlighted in red.
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What would be a primary reason for the annexation of Kaliningrad by the Soviets defined by physical geography?

proximity to the Soviet Union

historically Russian population

strategic location on the Baltic Sea

roots in Eastern Orthodoxy