Final answer:
The comma is the most common and easiest delimiter to work with when importing data into an Access database from a text file, due to the widespread use of CSV formats.
Step-by-step explanation:
Keith is looking to import data into an Access database from a text file and is inquiring about the most common delimiter that is the easiest to work with. When importing text files into databases, the comma is typically the most commonly used delimiter. This is because the use of commas to separate values in a list is standard and widespread, a format known as comma-separated values (CSV). CSV files are very popular and easy to work with because many programs, including database and spreadsheet software, can easily parse CSVs. The tab delimiter is another common choice, particularly because it is less likely to appear in the actual data, reducing the risk of misinterpretation. However, for compatibility and ease of use, the comma remains the preferred choice.