Final answer:
David should use Graph (z) to limit the amount of pay raises as it shows the percentage increase in wages over the years.
Step-by-step explanation:
David should use Graph (z) to limit the amount of pay raises. Graph (z) displays the percentage increase in wages over the years, while Graph (w) displays the wages in millions. The goal is to limit pay raises, so David needs to focus on the percentage increase rather than the absolute values. Graph (z) shows that the percentage increase in wages decreases over time, indicating a slower growth rate and potentially limiting the amount of pay raises.