Books(isbn, title, date, retail) Bookauthor(authorid, authorname, isbn) Which of the following is an example of an equality join?

Select one:

a.None of the above.

b.SELECT title, authorid FROM books, bookauthor WHERE books.isbn = bookauthor.isbn and retail>20;

c.SELECT title, name FROM books cross join publisher;

d.SELECT title, gift FROM books, promotion WHERE retail>= minretail and retail <= maxretail ;