In a scatter plot or line graph where you are examining the relationship between two variables (in this case, years of schooling and annual income), the convention is to place the independent variable on the x-axis and the dependent variable on the y-axis.
Since the years of schooling can be considered the independent variable that influences the dependent variable (annual income), you would plot the annual income on the y-axis.
Therefore, the data that would be plotted on the y-axis is:
B. Annual income