This question is based on the following table.

Household Income Average number of car per household

Less than $20,000 1.1

$20,000 --- $29,999 1.5

$30,000 --- $39,999 1.9

$40,000 --- $49,999 2.3

$50,000 --- $74,999 2.6

$75,000 --- $99,999 2.9

$100,000 --- $124,999 3.1

$125,000 --- $149,999 3.3

$150,000 and over 3.7

The relationship between household income and average number of car per household is:

Group of answer choices

a. Indirect.

b. Direct.

c. Terminal.

d. Fluctuating.

e. Nonexist