23. Select the incorrect statement regarding the contribution margin income statement.

	1.Assuming no change in fixed costs, a $1 increase in contribution margin will result in a $1 increase in profit.
	2.The contribution margin approach requires that all costs be classified as fixed or variable.
	3.Contribution margin represents the amount available to cover product costs and thereafter to provide profit.
	4. The contribution margin approach for the income statement is unacceptable for external reporting.