The_____ operation allows the combining of two relations by merging pairs of tuples, one from each relation, into a single tuple. SelectJoinUnionIntersection

The correct answer is Join.

Explanation

The Join operation in relational databases combines two relations (tables) by matching tuples based on a common attribute or set of attributes. When two relations are joined, the result is a new relation containing the attributes of both original relations, with tuples merged based on the specified conditions.

In contrast, Union combines the tuples of two relations without duplicates but does not merge them into single tuples. Intersection finds common tuples between two relations, while the "select" operation is used to choose specific tuples from a relation based on a criterion.

Thus, Join is the operation that specifically focuses on merging tuples to create a combined result based on shared attributes.