What is true about the graph of a linear function?

A linear function is defined by its consistent rate of change, represented mathematically by the equation (y = mx + b), where (m) is the slope and (b) is the y-intercept. The key characteristic of a linear function is that it produces a graph that is a straight line when plotted on a Cartesian coordinate system. This straight line indicates that for every change in the input (x), there is a proportional and predictable change in the output (y).

Therefore, the correct answer highlights that the graph of a linear function is a straight line, distinguishing it from other types of functions that may exhibit curves or more complex behavior. This unique property of linear functions is why they are foundational in algebra and are commonly studied when learning about functions and their graphs. The other options do not accurately represent the characteristics of linear functions, as linear functions are defined precisely in terms of their straight-line graphs and consistent output behavior.