Use the graph to answer the free$-$response question. Show any calculations and be sure to label your response.

A market graph shows quantity on the horizontal axis and price in dollars on the vertical axis. A curve labeled MC swoops downward then upward to the right. A u shaped curve labeled ATC intersects MC at $18$ units, $8$ dollars. Another u shaped curve labeled AVC is below ATC. AVC intersects MC at $14$ units, $4$ dollars. Additional points on the MC line are identified $10$ units, $2$ dollars; $15$ units, $6$ dollars; $22$ units, $10$ dollars.

Assume that the firm above operates in a perfectly competitive market.

Which labeled price$($s$)$ could be the market price if this firm is earning positive economic profits?

Explain how the short$-$run price$($s$)$ from part $($a$)$ could get to the long$-$run equilibrium price level.

At which labeled price$($s$)$ from the graph would the firm operate in the short run but leave the market in the long run?

If the short$-$run market price is $$8,$ what will this firm's total revenue be$?$

If the government instituted a per$-$unit tax, which curve$($s$)$ above would move?