4. One of the best known early theoretical models of development that focused on the structural transformation of a primarily subsistence economy was formulated by Nobel laureate W. Arthur Lewis in the mid-1950's. The Lewis two-sector model became the general theory of the development process in surplus-labor developing nations during most of the 1960s and early 1970s. Briefly discuss TWO (2) criticisms of the Lewis model. [4 Marks]