What was the name of the first roll film camera

Kodak. On September 4, 1888, George Eastman received a patent for a roll-film camera and registered the trademark “Kodak.”  The name “Kodak” came from Eastman’s fondness for the letter “K.” He found it a “strong, incisive sort of letter.” He and his mother devised the name Kodak with an anagram set.

Where are the following ?

high entry costs prevent new producers from entering the market.

explanation:

an oligopoly is a term used to clarify the structure of a particular market, industry, or organization. a market is considered oligopolistic or amazingly focused when it is shared between a few companies.