Figure 4-18 Figure 4-18 Shows the Market for Cigarettes

Figure 4-18 Figure 4-18 shows the market for cigarettes. The government plans to impose a per-unit tax in this market.
-Refer to Figure 4-18. What is the size of the per-unit tax?

A) $8
B) $5
C) $3
D) cannot be determined from the figure