If the opportunity cost of producing more of one good increases as more of that good is produced, then the production method is inefficient

The labor supply curve faced by an individual firm in a perfectly competitive market is

A) upward sloping. B) horizontal. C) vertical. D) downward sloping.

The cross price elasticity of demand between two goods will be positive if

A) the two goods are complements. B) the two goods are substitutes. C) the two goods are luxuries. D) one of the goods is a luxury and the other is a necessity.