To answer this question, we need to understand the concept of a mandatory one-to-one relationship in database modeling.
A mandatory one-to-one relationship indicates that each entity in one table must be associated with exactly one entity in another table, and vice versa. In other words, it means that every record in one table must have a corresponding record in the other table, and vice versa.
Let's go through each option to determine which one is correct:
Option A) More entities are needed - This option is incorrect. A mandatory one-to-one relationship does not imply that more entities are needed. It simply means that each entity in one table must have a corresponding entity in another table.
Option B) The model should be denormalized - This option is incorrect. A mandatory one-to-one relationship does not necessarily indicate that the model should be denormalized. Denormalization is a technique used to improve performance in certain situations, but it is not directly related to the presence of a mandatory one-to-one relationship.
Option C) The tables are not properly indexed - This option is incorrect. The presence of a mandatory one-to-one relationship does not necessarily indicate that the tables are not properly indexed. Indexing is a separate concept that is used to improve the performance of database queries.
Option D) The model cannot be implemented physically - This option is incorrect. A mandatory one-to-one relationship does not imply that the model cannot be implemented physically. It simply means that there is a requirement for a one-to-one relationship between entities in two tables.
Option E) More attributes are needed - This option is correct. A mandatory one-to-one relationship can indicate that more attributes are needed in either of the tables involved in the relationship. Since each entity in one table must be associated with exactly one entity in the other table, it may require additional attributes to properly capture the relationship.
Therefore, the correct answer is option E) More attributes are needed. This option is correct because a mandatory one-to-one relationship can indicate that additional attributes are needed in either of the tables involved in the relationship.