Assertion. A unique value that identifies each row uniquely is the primary key.

Reason. Only one column can be made the primary key.

(c)

Assertion is true but Reason is false.

Explanation
A primary key is a set of one or more attributes (columns) that can uniquely identify tuples within the relation. When a primary key is made up of two or more attributes, it is called as composite primary key. Hence, the reason is false.