In order to study how changing price affects consumer decisions, we must assume all other factors, such as income and the prices of other goods are constant. This assumption is best know as

Refer to the figure above. What is the initial equilibrium price of the good?

A) $20 B) $40 C) $60 D) $80

Using the textbook's production function, if two percent more labor working with two percent more capital produces two percent more real GDP, then "multifactor productivity" has

A) risen by four percent. B) risen by two percent. C) remained unchanged. D) fallen by one percent. E) fallen by two percent.