1. Positive economic profits earned by existing firms in a perfectly competitive market will eventually lead to:

1. exit of the firms from the market.

2. a decrease in the aggregate supply.

3. the existing firms emerging as price makers.

4. entry of new firms into the market.

5. an increase in the market price of the good.

2. The demand curve faced by a perfectly competitive firm is:

1. relatively elastic.

2. unit elastic.

3. perfectly inelastic.

4. perfectly elastic.

5. relatively inelastic.

3. An individual perfectly competitive firm's supply curve is its:

1. total cost curve.

2. marginal cost curve.

3. average-variable-cost curve.

4. marginal revenue curve.

5. average-fixed-cost curve.