A customer reports that a text-only document prints with unrecognizable characters. The print preview correctly displays the document. Which of the following is the most likely cause of the issue?

While outdated firmware can cause various printing issues, it is less likely to specifically result in unrecognizable characters if the print preview is correct. Firmware primarily affects the printer's operational capabilities rather than the interpretation of print jobs, making it a less probable cause in this scenario.

A bad toner cartridge typically results in printing issues like streaks, smudges, or faded output, rather than unrecognizable characters. If the cartridge were malfunctioning, the print would likely still reflect the intended text but in a degraded form, which does not align with the problem described.

A corrupted document file can cause printing problems, but if the print preview displays correctly, this indicates that the document is likely intact. A corrupted file would typically show issues in both the preview and the print output, making it an unlikely cause of the issue reported by the customer.