Answer:
The human capital theory
Step-by-step explanation
The human capital theory explores the relationship between investment in human capital and earnings.
Investment in human capital can take the form of education or training.
The theory suggest that those that invest in human capital earn higher income
The human capital theory also explores pattern of earnings. The theory suggests that the earnings of young people would be low as they would forgo earnings to invest in human capital . Earnings would increase as one gets older because old people invest less in education and training