Consider the following examples of prices. For each example, determine whether or not price discrimination exists and explain why or why not. Graphs are welcome but not required. [Hint: Evaluate the conditions that must exist for price discrimination to hold]

a. Designer or custom license plates are much more expensive compared to regular license plates.

b. On the Paris metro First Class and Second Class compartments used to be identical, except for the signs "First Class" and "Second Class," and the higher fare for riding first class.

c. Electricity, consumers are charged different prices depending on the quantity of electricity they consume. For example, the first 100 units consumed are priced higher than the units beyond 100.