If a perfectly competitive firm sells 50 units of output at a market price of $10 per unit, its marginal revenue is:

According to the monetarist view, the aggregate supply curve is:

A. Horizontal until full employment is reached and then it becomes vertical. B. Horizontal at all levels of output. C. Vertical at the natural rate of unemployment. D. First horizontal, then upward sloping, and finally vertical.

Suppose a frost destroys the tomato crop in California but farmers see an increase in their revenues. Which of the following best explains this?

A) Tomatoes are necessities. B) The demand for tomatoes is price inelastic. C) The decrease in supply led to huge price increases. D) The cross-price elasticity between tomatoes and most other substitute vegetables is very low.