Steelweld, a car parts manufacturer, pays employees a higher hourly rate as they learn to master more tasks on the production floor. Employees earn $15 per hour when they are hired and they can earn up to $28 per hour if they master all 12 work units in the production process. Steelweld is applying which of these reward systems?
a. Skill-based pay
b. Piece-rate pay
c. Job evaluation system
d. Commission-based pay
e. Seniority-based pay