Explanation:

A weak entity set is an entity set that does not have sufficient attributes to form a primary key on its own. It relies on a strong entity set to provide a partial or total key.

To understand which set should be associated with a weak entity set to be meaningful, let's consider the options:

a) Neighbour set: This set refers to the neighboring entities of the weak entity. While it may be related to the weak entity, it does not necessarily provide a key for the weak entity set. Therefore, it is not the correct option.

b) Strong entity set: A strong entity set is an entity set that has a primary key on its own and does not depend on any other entity set. Since a weak entity set relies on a strong entity set, associating it with a strong entity set is necessary to form a meaningful relationship. However, it is not the correct option for this question.

c) Owner set: The owner set refers to the entity set that owns or has control over the weak entity set. While the owner set may have a relationship with the weak entity set, it does not provide a key for the weak entity set. Therefore, it is not the correct option.

d) Identifying set: An identifying set is a set of attributes in a strong entity set that uniquely identifies each entity in the weak entity set. This means that the identifying set is used to form a partial or total key for the weak entity set. Therefore, associating the weak entity set with the identifying set is necessary for it to be meaningful.

Conclusion:

In order for a weak entity set to be meaningful, it needs to be associated with the identifying set from a strong entity set. This ensures that the weak entity set can be uniquely identified and related to the strong entity set.