A data item, which is not broken down into smaller units, isOptionsData elementData entryDatabase managementElementary data item

In the context of data management, the term that best describes a data item which is not broken down into smaller units is typically referred to as an Elementary Data Item. An elementary data item is a basic unit of data that is indivisible—for example, a single value or attribute such as a person's name, age, or address that cannot be further decomposed into smaller parts in the context of a database.

Here’s a brief explanation of the other options for clarity:

1. Data Element: This often refers to a combination of one or more elementary data items, hence it can be broken down further.

2. Data Entry: This represents the act of inputting data into a system, rather than the data itself.

3. Database Management: This relates to the administration of database systems and does not refer to a specific unit of data.

Therefore, the most accurate answer is Elementary Data Item.