A. The minimal set of attribute that uniquely identifies each occurrence of an entity type
B. Set of one or more attribute that can be used to uniquely identify the records in a table
C. The candidate key that is selected to uniquely identify each occurrence of an entity type
D. A candidate key that consists of two or more attributes
Explanation
In database design, a composite key is a candidate key that consists of two or more attributes (table columns) that together uniquely identify an entity occurrence (table row).
A compound key is a composite key for which each attribute that makes up the key is a simple (foreign) key in its own right.
