Which of the following results in each related entity set having its own…

When an ER diagram is converted into relational schemas, how a relationship set is represented depends on its cardinality. A one-to-one relationship can be merged into either connected entity's schema. A one-to-many relationship can be merged into the schema of the entity set on the 'many' side, using a foreign key. A many-to-many relationship set, however, cannot be captured by a foreign key on either side without duplicating rows or losing information, so it always needs its own separate schema -- carrying the primary keys of both entity sets (plus any relationship attributes) -- in addition to the two entity sets keeping their own independent schemas.

The scenario described -- every related entity set retains its own schema, and a further, additional schema exists purely to represent the relationship -- is exactly this many-to-many case: the relationship set needs a dedicated schema of its own precisely because it cannot be absorbed into either entity's table.

• A one-to-many relationship set does not need an extra schema -- it is absorbed into the 'many' side's schema via a foreign key, so it does not match the scenario.

• A multivalued attribute of an entity set does get its own separate schema, but that schema stores values of a single entity set's attribute -- it is not a schema for a relationship connecting two entity sets, so it does not match the scenario either.

• 'None of the mentioned' would only apply if no listed case produced this exact schema split, but one of the listed relationship types genuinely does.

Hence, the case that forces each entity set to keep its own schema while requiring a genuinely additional schema for the relationship itself is a many-to-many relationship set.