If scarcity were eliminated,

When economists say the demand for a product has decreased, they mean

As a general rule, technological progress

Modern economics as a field of study is usually thought to have begun with

An income tax is proportional if

An increase in the demand for a product will cause the

The imposition of price ceilings on a market often results in

When economists say the supply of a product has decreased, they mean that

In voluntary exchange, if the seller of a product gains,

Two goods are considered substitutes only if