The question is asking which of the three graphs in the image represents a linear function, which follows the form $y = ax + b$.

Looking at the graph:

• The yellow graph is a straight line, which is characteristic of a linear function because it has the form $y = ax + b$ (a straight line).
• The orange graph and the blue graph are curved, meaning they cannot represent linear functions. They likely represent higher-degree polynomial functions or other non-linear types.

So, the yellow graph is the graph of a linear function.

Would you like further details or have any other questions?

Here are some related questions:

1. How can you recognize a linear function from its equation?
2. What are the characteristics of a polynomial graph?
3. What are the effects of changing the slope $a$ and intercept $b$ in the equation $y = ax + b$?
4. Can a quadratic or cubic function ever appear as a straight line?
5. How do you determine the degree of a polynomial function from its graph?

Tip: Linear functions always produce straight lines, whereas non-linear functions (like quadratics or cubics) result in curves.