A As the side length increases by 1, the area does not increase or decrease by an equal amount.

B
As the side length increases by 1, the area increases and then decreases by an equal amount. the area increases and then decreases by an equal factor.

C
As the side length increases by 1, the area does not change.

D
As the side length increases by 1, the area increases and then decreases by an equal factor.