Three relationships are described below:
I. The amount of fuel used on a trip increases as the size of the car increases and as the distance traveled increases.
II. As the number of people helping mow a lawn increases, the time it takes to mow the lawn decreases.
III. The cost of having a house painted increases as the size of the house increases.
What type of variation describes each relationship?
A)I is joint, II is direct, and III is inverse.
B) I is joint, II is inverse, and III is direct.
C) I is direct, II is inverse, and III is joint.
D) I is direct, II is joint, and III is inverse.