सूची I को सूची II के साथ सुमेलित कीजिए: सूची I A. हैरोड अस्थिरता (Harrod instability) B. सोलो स्थिर अवस्था (Solow steady state) C. काल्डोर तथ्य (Kaldor fact) D. रोबिन्सन वृद्धि (Robinson growth) सूची II I. छुरी की धार संतुलन (Knife-edge equilibrium) II. स्थिर पूंजी-उत्पादन अनुपात (Constant capital-output ratio) III. लाभ-संचालित संचय (Profit-driven accumulation) IV. अभिसरण क्रियाविधि (Convergence mechanism)

Given below are two statements, one labeled as Assertion (A) and the other as Reason (R): Assertion (A): Rostow suggested that underdeveloped economies should invest 20% of national income in capital formation to accelerate economic development. Reason (R): According to Rostow, raising the rate of saving and capital formation determines the pace of economic development in underdeveloped countries. In light of the above statements, choose the correct answer from the options given below:

According to the Lucas Growth Model, what is the central driver of long-term economic growth?