One of the Main Sources of Disagreement Amongst Economists About

One of the main sources of disagreement amongst economists about macroeconomic policy is

A) a fundamental disagreement about the role of taxation.
B) how far and how quickly macroeconomic variables adjust in response to changing economic conditions.
C) whether the marginal propensity to consume can be calculated accurately.
D) whether the IS-LM model has any relevance at all to a modern developed economy.