Which of the following indicates the maximum number of entities that can be involved in a relationship?

Answer: Option B

Option A: Minimum cardinality
Minimum cardinality defines the least number of entities that must participate in a relationship. It typically specifies the mandatory aspect of a relationship. For instance, in an employee-manager relationship, a department may need at least one manager.

Option B: Maximum cardinality
Maximum cardinality indicates the upper limit on the number of entities that can participate in a relationship. It specifies the maximum number of instances an entity can be associated with another entity in a relationship. For example, in a one-to-many relationship, the maximum cardinality would denote the "many" side of the relationship.

Option C: ERD
ERD stands for Entity-Relationship Diagram, which is a graphical representation of entities and their relationships. While ERDs visually display cardinality, they are not the direct indicators of the maximum number of entities in a relationship.

Option D: Greater Entity Count (GEC)
This option is not a standard term in data modeling or the ER model. It does not pertain to defining the number of entities involved in a relationship.

Conclusion:
The correct answer is Option B: Maximum cardinality because it directly specifies the maximum number of entities that can be involved in a relationship.