When Graphing the Consumption Function, What Purpose Is Served by the 45-Degree

Multiple Choice

When graphing the consumption function, what purpose is served by the 45-degree line?

A) It identifies all the points at which saving and consumption spending are equal.
B) It identifies all the points at which real disposable income and planned real consumption spending are equal.
C) It identifies all the points at which real planned investment expenditure and real autonomous consumption spending are equal.
D) It identifies all the points where real dissaving and saving are equal.