For each of the scenarios in the following table, indicate the most likely reason for the difference in earnings. Differences in Differences in Differences in Skills and Job Worker Scenario Human Capital Preferences Age Preferences Two automotive technicians have the same amount of schooling and work experience but earn different wages. The first works the day shift for an auto manufacturer factory for an annual wage of $55,000 per year, and O O O O the second works the night shift for the same company for an annual wage of $60,000 per year. Maria, a 50-year-old doctor with 20 years of experience, earns more than Rajiv, a 30-year-old doctor just out of medical school with the same skills O O O O and field of specialization. An economics consulting firm hires Crystal, a recent Ph.D. graduate in economics, and pays her an annual wage of $72,000. It also hires Kevin, a O O O O recent master's degree graduate in economics and pays him an annual wage of $60,000. Juanita earns an annual salary of $70,000 as a financial analyst for a large accounting firm. Lorenzo works in a similar position (with similar experience and productivity) as Juanita but for a rival accounting firm that O O O O offers its employees free child care and a free gym at work. Lorenzo earns a salary of $55,000 per year