Which of the following indicate the marginal external cost and the socially optimal quantity?

Why is age an important determinant in decisions regarding migration? a. age influences the ability of migrants to adapt to new cultures. b. older migrants are more likely to move in search of work. c. age influences the likelihood that host nations will accept an immigrant. d. young adults are unlikely to move far from their families. e. older migrants are more likely to move far from their families.