Garbled print output is typically due to a communication problem between the computer and the printer. It can be caused by an incorrect driver, a corrupted file, or a faulty cable. Checking and updating the printer driver is often the first step in resolving these kinds of issues because drivers translate the computer's instructions into a format that the printer can understand. If the driver is incorrect or outdated, the instructions can become jumbled, leading to garbled prints. Other options listed are less likely to cause garbled print output but can be sources of other types of print defects.