​The Following Diagram Shows Ken's Demand Curve for Neckties

Multiple Choice

​The following diagram shows Ken's demand curve for neckties. Point a on the curve shows that when the price of neckties is $5, Ken purchases four neckties. Point b on the curve shows that when the price of neckties falls to $4, he purchases five neckties. At point b, the dollar value of the total utility is valued at: ​
Figure 6.3
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A) $30.
B) $26.
C) $20.
D) $35.
E) $25.