Final answer:
A cursor is an iterator that retrieves data from a database query result set.
Step-by-step explanation:
A cursor is an iterator that specifies a query that may have a set of tuples. In the context of databases, a cursor is used to traverse and retrieve data from a database query result set in a sequential manner. It is typically used in programming languages like SQL or Python to interact with a database and perform operations on data. A cursor in the context of databases is a database object used by applications to manipulate data in a set on a row-by-row basis, essentially acting as an iterator to traverse records. When discussing a query that may have a set of tuples, the most appropriate option is B. Database. In databases, a cursor allows for controlled navigation and data retrieval, such as selection, updating, and deletion for individual rows. Cursors are fundamental in transaction processing and complex data manipulation within a database management system (DBMS).