A company increased the price of gasoline by $$2.$ This was followed by a public outcry against the price increase. A year later, the company increased the gasoline price by $$1.$ This time, the public accepted it as essential, though there was a general murmur of dissatisfaction. Which of the following best explains the reason for the public's acceptance?

a$.$ Theory $x$

b$.$ Skinner's law

c$.$ Weber's law

d$.$ Equity theory