Which of the following statements is correct? a. Increased globalization and technological progress can both be blamed, at least to some extent, for the increase in wage inequality in the United States. b. In the U.S., Many spells of unemployment are short but that most weeks of unemployment are attributable to the long-term unemployed. c. The high unemployment in Europe is probably due to, among others, generous UI benefits, and strong union presence. d. The natural rate of unemployment includes structural and frictional unemployment