Answer
See the explanation
Work Step by Step
a. **Designer of the DBMS software**: Concerns related to how data should be stored on a disk to maximize efficiency fall within the domain of the database management system (DBMS) designer, as they are responsible for designing the storage structures and algorithms to optimize performance.
b. **User**: Checking for the vacancy on flight 243 is a user-level concern, as it involves querying the database for specific information.
c. **Designer of the DBMS software**: Organizing a relation in mass storage is a concern that resides with the designer of the database management system. They determine the physical storage layout and access methods for relations.
d. **Programmer of application software**: The decision on how many times a user should be allowed to mistype a password before terminating the conversation typically involves application logic and is implemented by the programmer of the application software.
e. **Programmer of application software**: Implementing the PROJECT operation (selecting specific columns from a table) is a concern typically handled by the programmer of the application software, as it involves writing the appropriate query or code to perform the operation.
