Which of the following is NOT a reason for expecting that a cause-and-effect relationship exists between the level of an activity and specified costs.
a. management's knowledge of "how things operate" is a basis for asserting cause and effect.
b. there is a high correlation between the level of an activity and specified costs.
c. a physical relationship exists between the level of activity and costs.
d. a contract specifies that higher activity results in higher costs.