Which one of the following is used to represent the supporting many-one relationships of a weak entity set in an entity-relationship diagram ?

In an Entity-Relationship Diagram (ERD), the supporting many-one relationships of a weak entity set are represented by a double diamond.

Here are the steps to understand this:

1. In an ERD, entities are represented by rectangles, relationships are represented by diamonds, and attributes are represented by ovals.

2. A weak entity is an entity that cannot be uniquely identified by its attributes alone; it must use a foreign key in conjunction with its attributes to create a primary key.

3. The relationship between a weak entity and its supporting entity is represented by a double diamond, not a single diamond. This is because the weak entity is dependent on the supporting entity for its existence.

4. The line connecting the weak entity to the double diamond is a double line, indicating total participation of the weak entity in the relationship. This means every instance of the weak entity is associated with an instance of the strong entity.

5. The line connecting the strong entity to the double diamond is a single line, indicating that the strong entity does not necessarily participate in the relationship.

So, the double diamond in an ERD is used to represent the supporting many-one relationships of a weak entity set.