The "Big Push" theory of economic development, associated with Paul Rosenstein-Rodan, relies primarily on which economic mechanism?

Rosenstein-Rodan’s Big Push theory argues that developing economies may remain trapped at low levels of industrialisation because isolated investments may not be profitable. The theory emphasises two important ideas: 1. Indivisibilities Certain investments require large minimum scales. Infrastructure, factories, transport systems and power generation often involve high fixed costs and cannot be efficiently undertaken on a very small scale. 2. Demand Complementarities If many industries invest simultaneously, workers employed in one industry generate demand for the products produced by other industries. For example, workers employed in Factory A may use their income to purchase goods produced by Factory B. Workers in Factory B may similarly purchase products produced by Factory A. Therefore, coordinated investment across many industries can expand the market and make investments profitable that would not have been profitable individually. This coordinated large-scale investment programme is called the "Big Push."