Please select the competitive markets in below scenarios.
A. In a small town, there are two providers of broadband Internet access: a cable company and the phone company. The Internet access offered by both providers is of the same speed.
B. Dozens of companies produce plain white socks. Consumers regard plain white socks as identical and don't care about who sells them their socks. The technology for producing socks is widely known, and any reputable person who wanted to start a sock manufacturing business could obtain a loan from a bank to buy the necessary machinery.
C. Scholastik Inc. owns the U. S. copyright to a popular book series. It is the only company with the legal right to publish books in the series in the United States.
D. Several stores in the mall sell hooded sweatshirts. Each store's sweatshirts reflect the style of that particular store. Additionally, some stores use higher-quality cotton than others, which is reflected in the apparel's prices.