Identify the level within a database system (user, programmer of application software, 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 and save disk space?
b. What is the current balance of student X?
c. How should a relation be organized in mass storage?
d. How many times should a user be allowed to mistype a password before the application terminates?
e. How can the JOIN operation be implemented?