Which method is suitable for importing a file that varies each time?

The method of "Overwrite" is suitable for importing a file that varies each time because it replaces the existing data with new data from the file being imported. This ensures that all previous entries are removed and only the latest information remains in the system. This is particularly useful when dealing with files that have a changing dataset, as it eliminates the risk of duplicating old entries or retaining outdated information.

In contrast, the other methods do not fully align with scenarios where the file content changes frequently. For example, "Add Only" would only add new entries without touching existing data, which could lead to inconsistencies if the data has changed. Similarly, "Add and Update" might be appropriate in contexts where some new entries need to be added while also updating existing records, but it does not guarantee a complete replacement of old data. The "Update" method can modify existing records but does not inherently deal with varying data where the entire content needs to be refreshed with new information. Thus, "Overwrite" is the most efficient and effective method for the described situation.