Suppose an economy's production function is given by Y = AK^0.25L^0.75. If the annual growth rate of output is 10 percent and labour and capital are growing at 2 percent and 4 percent, respectively, what contribution to output growth is made by total factor (or multi-factor) productivity? * 4 percent growth. * 8 percent growth. * 7.5 percent growth. * 2.5 percent growth. * 12 percent growth