10. Optimization of consumer spending best takes place where: (a) the consumer's budget constraint is tangent to his/her highest indifference curve between current and future spending; (b) there is online access to Amazon; (c) savings rates are the highest; (d) marginal tax rates are the highest. 11. Demand for U.S. Treasury securities globally increased sharply in 2020. One possible partial explanation for the surge in demand, despite their low nominal yields, might be: (a) these securities are backed by the full faith and credit of the New York Fed against default; (b) U.S. inflation expectations are unusually high for years, if not decades, to come; (c) the default of the European Central Bank created a risk-off environment in European markets; (d) while relatively low historically, yields on Treasuries are higher than those of comparable securities issued by other major countries