In both curves (C) and (D), with the increase of value x, dependent variable y increases. But these two curves have different shapes.
How will we describe the differences between the curve (C) and (D)? As both curves indicate a positive relationship between independent variable, x, and dependent variable, y, why/how do these two curves take different shapes?
I like to learn these differences in a descriptive manner. That means- without using any equation (if it is possible, or as much as possible), their differences will be described.