The attributes which have all the properties of primary key
(A) Foreign key
(B) Alternate key
(C) Candidate key
(D) Both (a) and (c)
A primary key is an attribute which can uniquely identify the records in a relation/table.
Checking the options
- (A) Foreign key - It is an attribute used to represent the relationship between two tables/relations.
- (B) Alternate key - It is a candidate key which has not been selected to be the primary key.
- (C) Candidate key - refers to the set of all attributes which can uniquely identify records in a relation.
- (D) Both (a) and (c)
Since candidate keys can also uniquely identify records in a relation, it has similar properties to primary Key.
So, the correct answer is (C)