Cohesion funds are used to make EU countries more culturally similar

When aggregate expenditure increases, why is there a multiple expansion of income and real GDP? Trace the multiplier effect through the first four rounds when there is an increase in aggregate expenditure of $40 billion and the marginal propensity to consume is 0.75

Sources of increasing returns that help raise productivity growth include the following, except:

A.  More specialized inputs B.  Spreading of development costs C.  Network effects D.  Low unemployment