Which of the following file organization requires a primary key

The file organization that requires a primary key is the indexed file organization. In indexed file organization, the data is stored in a primary file, and an index file is created to keep track of the location of each record in the primary file. The index file contains a list of keys and their corresponding record pointers, which are used to access the actual data in the primary file. A primary key is required in indexed file organization because it uniquely identifies each record in the primary file. This key is used to build the index file, and it must be unique for each record to ensure that the index file accurately maps the location of each record in the primary file. Without a primary key, it would be difficult to search for a specific record in the primary file or maintain the integrity of the index file. In summary, the indexed file organization requires a primary key because it relies on the uniqueness of the key to accurately map the location of each record in the primary file.