The correct answer is B. experience curve.
An experience curve is a graph that shows the relationship between cumulative output and unit cost. It is based on the idea that as a company produces more of a product, it learns how to produce it more efficiently, which leads to lower costs.
A mixed curve is a graph that shows the relationship between two or more variables. It is used to represent situations where there is no clear relationship between the variables.
A discrete curve is a graph that shows the relationship between two variables that are not continuous. It is used to represent situations where the variables can only take on certain values.
A fixed curve is a graph that shows the relationship between two variables that are always constant. It is used to represent situations where the variables do not change.
The experience curve is the most appropriate answer to the question because it is used to measure decline in per unit cost of different business functions.