Which of the Following Is Not an Example of a Barrier

Multiple Choice

Which of the following is not an example of a barrier to entry?

A) John owns the only parcel of lakeside property with a beach that is safe for swimming. He charges admission to neighbors who want to use the beach.
B) Jackie owns the copyright to a popular song. She receives royalties every time a radio station plays her song.
C) John Jr. owns the best seafood restaurant in a popular resort area. He charges high prices because the quality of the food is so good.
D) Caroline owns the patent for a new running shoe. She receives payments from the company who manufactures the shoes.