Which one of the descriptions is correct regarding the following Entity$-$Relationship diagram?

An employee can have several addresses kept in the database.

Age can be derived from other attributes in the database.

Each employee should provide one and only phone number to be kept in the database.

By using either Name or Date$\_$Of$\_$Birth, a unique employee can be identified.

Date$\_$Of$\_$Birth is not a required attribute for EMPLOYEE.