It is best to store the data just once. For this purpose, which of the following is often the best choice? Worksheet Data Model Single-table database Flat file

**Step 1. Understand the Options** We are given four options and asked: _"It is best to store the data just once. For this purpose, which of the following is often the best choice?"_ - **Worksheet:** Commonly refers to a spreadsheet document. While spreadsheets are useful for analysis and presentation, they are not ideal for ensuring that data is stored only once. They tend to encourage data duplication if used across multiple files or sheets. - **Data Model:** Refers to an abstract, conceptual representation of data. It establishes rules, relationships, and structures (often through normalization) that ensure each piece of data is stored in one place only, thereby reducing redundancy. - **Single-table database:** Although a database might primarily store data in tables, using a single table might lead to redundant data if the table is not well-designed, especially when multiple types of information are involved. - **Flat file:** A simple file that stores data without structured relationships. It often leads to data duplication and difficulties in maintaining referential integrity. **Step 2. Choosing the Best Option** Since the question emphasizes storing data just once (thereby reducing redundancy and potential inconsistencies), the best approach is to use the concept of a **Data Model**. A well-designed data model, such as one used in a relational database with normalized tables, ensures that each fact is stored only once and can be related to other data via keys and relationships. **Step 3. Conclusion** Thus, the best choice is: \[ \textbf{Data Model} \]