Which of the Following Is True About Identifiers of Entities

question 77

Multiple Choice

Which of the following is true about identifiers of entities?

• A) Identifiers must be unique.
• B) Identifiers are not normally used in a naming role.
• C) The value of an identifier may identify a set of entity instances.
• D) Identifiers may not be more than two attributes.
• E) An identifier in the E-R model is equivalent to a key in the relational model.