Which forms have a relation that contains information about a single entity?

A table is in its 3rd NF if it has already completed in 2NF, and non-key attributes are not dependent on any non-key attributes. This means that all non-key attributes must depend on primary key. When a table represents a single entity, the primary key will identify the instance row and all attributes in 3NF are dependent on the primary key. So, the primary key in the 3th NF captures the whole information of this single entity.