Answer:
The correct option is C.
Step-by-step explanation:
The proportional relationship between x and y is defined as


Where, k is constant of proportion.
In option A, the rate of change is constant because the value of y increased by 4 as the value of x increased by 1.
If a line passing through two points, then the equation of line is

The equation of a line


It is not in the form of
. So, option A is incorrect.
In option B, the rate of change is not constant because the value of y is not increasing by a constant rate the value of x increasing by 1. So, option B is incorrect.
In option C, the rate of change is constant because the value of y increased by 4 as the value of x increased by 1.
The equation of a line


It is in the form of
. So, option C is correct.
In option D, the rate of change is not constant because the value of y is not increasing by a constant rate the value of x increasing by 1. So, option D is incorrect.