If there are changes in the values of the exogenous variables in a model, we expect: the number of equations in the model will change. B. the number of exogenous variables will change C. the number of endogenous variables will change. D. none of the above. For the equation: Y - C = 100, the graph of the equation with Y on the horizontal axis and C on the vertical axis is: A. a vertical line. B. a downward sloping line (from left to right). C. a horizontal line. D. none