Trisha is the owner of Garden Tools Inc. and she is looking to determine the HR demand of production staff for next year. Trisha begins by comparing the company's current sales with the number of production staff that contributed to it. Since the sales forecast show a 20% increase, Trisha concludes that a 20% increase in staffing for production staff will be required.
What method is Trisha following to determine HR Demand?

a. Indexation
b. Nominal group technique
c. Delphi technique
d. Extrapolation