which of the following statements regarding a linear cost function is true? 1- the slope coefficient of a mixed cost line intersects the vertical axis at zero 2- it is easier to identify a single measure of benefit in a more heterogeneous cost pool 3- when there are only fixed costs total material costs increase as the number of units produced increases 4- a linear cost function for manufacturing overhead can be graphed when their is a cause and effect relationship between the level of activity and the costs related to that level of activity 5- the relationship between the cost driver and the fixed cost is represented by the cost benefit relationship