Answer:
1) Yes, Publisher relation should have a publisherID primary key.
2) NOT NULL and UNIQUE for the BookID, BranchID, CardNumber and name of the borrower in the Book, Book_Copies, Library_branch, and Borrower relations respectively. The DueDate field of the book_loan relation must be a time constraint. The BookID of the Book relation must be serial number for automatic addition and update of bookid across the database.
Explanation:
The Publisher relation should have primary key publisherID which should replace the publisherName in the Book relation to easily make a join query and attain a third-level database model.
Answer:
The Answer is gonna be D. Zero decimal
An Object Class. Hopefully this answer is right.