In a relational database, what is a “tuple” ?

In relational database theory, a tuple is formally defined as a single row within a table. Each tuple represents one specific record containing data about an entity, such as a single customer or product. The collection of all tuples in a table forms the relation itself, making "a row" the precise technical definition. Option B is incorrect because a column represents an attribute or field, not a tuple. Similarly, Option C refers to the entire relation (the table), and Option D refers to the database as a whole, which contains multiple tables. Therefore, understanding that a tuple corresponds directly to a row is fundamental for mastering relational database concepts and SQL query operations.