Explain why each of the following examples is not a perfectly competitive industry.
a. One firm produces a large portion of the industry's total output, but there are many firms in the industry, and their products are indistinguishable. Firms can easily exit and enter the industry.
b. There are many buyers and sellers in the industry. Consumers have equal information about the prices of firms' products, which differ moderately in quality from firm to firm.
c. Many taxicabs compete in a city. The city's government requires all taxicabs to provide identical service. Taxicabs are nearly identical, and all drivers must wear a designated uniform. The government also limits the number of taxicab companies that can operate within the city's boundaries.