An increase in the working-age population A. shifts the labour supply curve rightward. B. shifts the labour demand curve leftward. C. shifts the labour demand curve rightward. D. shifts the labour supply curve leftward. An increase in the working-age population A. shifts the production function downward. B. shifts the production function upward. C. results in movement down the production function. D. shifts the production function and results in movement along the production function. E. results in movement up the production function. .