(b) and (c) are functions (c) is a one-to-one function
Work Step by Step
To check if a graph is a function, we use the vertical line test. Graphs (b) and (c) pass the vertical line test, so they are functions. To check if a graph is one-to-one, we use the horizontal line test. Graphs (c) and (d) pass the horizontal line test, but only (c) is a function. So (c) is the only one-to-one function.