Answer: C. The price of gasoline increases but a traveling salesman increases his purchases of gasoline.
Step-by-step explanation:
With a few exceptions the Law of Demand states that, QUANTITY DEMANDED OF A GOOD MUST FALL IF PRICES OF SAME GOOD RISES.
The Price of gasoline has increased yet the Sales man purchases more gasoline. This violates the law because he should be buying less gasoline as prices have increased to keep his costs down.
Option B speaks to one of those aforementioned exceptions. The Diaper is an ESSENTIAL GOOD for the woman which means that she will keep spending regardless of price to get that good.