When enforcing minimum cardinalities in a relationship between two entities, how many distinct types of actions must be considered overall?

Introduction / Context:
Minimum cardinality expresses whether participation in a relationship is optional (0) or mandatory (1) for each entity. Enforcing these rules requires considering actions that occur on each side.

Given Data / Assumptions:

• Two entities participate in one relationship.
• Each side may have a minimum of 0 or 1.
• We are looking for the types of actions to enforce these minima.

Concept / Approach:
To enforce minimum cardinality you must ensure compliance from the perspective of each entity type: (1) actions taken when creating or updating an instance of the first entity and (2) actions taken when creating or updating an instance of the second entity. In practice these are enforced via constraints, triggers, or application logic that check required related instances from both sides.

Step-by-Step Solution:

Verification / Alternative check:
Design method guides often break enforcement by side: enforce "each A must have at least one B" and "each B must have at least one A" as separate checks.

Why Other Options Are Wrong:
Three/Four/Six: Overstates the number of fundamental enforcement directions; while there are many event points (insert/update/delete) the types collapse to two sides of the same relationship.

Common Pitfalls:
Confusing the number of minimum cardinality sets (four) with the number of enforcement directions (two). Also conflating minimum with maximum cardinality.

Final Answer:
Two