Which of the following does NOT contribute to the marginal productivity of workers?

If a person is taxed $100 on an income of $1,000 . taxed $220 on an income of $2,000 . and taxed $390 on an income of $3,000 . this person is paying a(n):

a. progressive tax. b. poll tax. c. regressive tax. d. excise tax. e. proportional tax.

A certain production possibilities frontier shows production possibilities for two goods, jewelry and clothing. Which of the following concepts cannot be illustrated by this model?

a. the flow of dollars between sellers of jewelry and clothing and buyers of jewelry and clothing b. the tradeoff between production of jewelry and production of clothing c. the opportunity cost of clothing in terms of jewelry d. the effect of economic growth on production possibilities involving jewelry and clothing