Which main characteristic is used to differentiate between strong and weak entities in the process...

Indatabase design, an entity is classified asstrong or weakbased on whether it has aprimary keythat uniquely identifies its records.

Differences Between Strong and Weak Entities:

CREATE TABLE Orders (

OrderID INT PRIMARY KEY,

CustomerID INT

);

CREATE TABLE OrderDetails (

OrderDetailID INT,

OrderID INT,

ProductID INT,

PRIMARY KEY (OrderDetailID, OrderID),

FOREIGN KEY (OrderID) REFERENCES Orders(OrderID)

);

Orders is astrong entity(has OrderID as its own primary key).

OrderDetails is aweak entity(depends on OrderID for uniqueness).

Why Other Options Are Incorrect:

Option A (Association) (Incorrect):Associations describerelationshipsbut do not define strong/weak entities.

Option C (Foreign key) (Incorrect):Weak entitiesdepend on foreign keys, butprimary keysdefine their status.

Option D (Cardinality) (Incorrect):Cardinality definesrelationship constraintsbut doesnot differentiate entity types.

Thus, the correct answer isPrimary key, as it is the defining characteristic betweenstrong and weak entities.