In the following question, some part of the sentence may have errors. Find out which part of the sentence has an error and select the appropriate option. If a sentence is free from error, select 'No error'. The reason for (1)/ his failure is because (2)/ he didn't study at all. (3)/ No Error (4)
A commodity market has a _________ structure, if there is one seller of the commodity, the commodity has no substitute, and entry into the industry by another firm is prevented.