Identify the level within a database system (user, programmer of application software, and designer of the DBMS software) at which each of the following concerns or activities occur:
a. How should data be stored on a disk to maximize efficiency?
b. Is there a vacancy on flight 243?
c. Could a relation be stored as a sequential file?
d. How many times should a user be allowed to mistype a password before the conversation is terminated?
e. How can the PROJECT operation be implemented?