pls help will give brainlist!!

which relationship does not represent a linear function?

A. The aunt population for a colony that begins with five ants and doubles in number every two weeks.

B. A history students grade on a test that begins at 100 but decreases by four points for each question answered incorrectly.

C. The amount of gasoline in a vehicle that begins with 22 gallons and decreases by 1 gallon every 28 miles.

D. The total cost of a large pizza based on $9.95 plus $.75 for each additional topping.

If we look at option A we see that the population of the colony starts with 5 ants and doubles every 2 weeks. This means in 2 weeks it reaches 10, about a month afterwards it reaches 20 and so on. A simple equation for this is:

[tex]5(2)^\frac{x}{2}[/tex] where x is the amount of weeks passed.

In option B we see that for every wrong answer, 4 points is deducted from 100. An equation for this is : 100 - 4x, whee x is the amount of wrong answers.

In option C we see that for every 28 miles 1 gallon is reduced an equation for this is: 22 - 1/28*x where x is amount of miles.

In option D we see that for every additional topping the price increases by .75 cents, 9.95 + 0.75x.

If you notice B, C and D are slightly different from A. If you notice for B, C and D the slope is constant for all equations. But for A the slope varies. This shows that A is not a linear equation. As for a linear equation the slope must be constant.