正解:D
Explanation
A thermal receipt printer uses heat to print on thermal paper, which has a special coating that reacts to heat and produces black marks. If the paper roll is inserted in the wrong orientation, the printer will not be able to print anything on the paper. Therefore, the first thing the technician should do is to check if the paper roll is loaded correctly, with the paper feeding under, not over. This is a common and easy mistake to fix, and it does not require any software or hardware changes.
References
*Troubleshooting Your Thermal Printer Problems - Thermal POS Receipt Printer Tips & Tricks, paragraph 2
*POS Thermal Receipt Printer Troubleshoot - Not Printing Evenly, video at 0:15
*Receipt Printer Troubleshooting - Shopfront, bullet point 2