Streaks and multiple lines on print jobs are commonly caused by an issue with the toner cartridge, such as a damaged or improperly installed cartridge. The technician should replace the toner first as it is the most likely and simplest component to check.
Why Not A (Rollers): Rollers primarily handle paper feeding and are less likely to cause streaking.
Why Not B (Drum): While the drum can cause similar issues, the toner cartridge is easier to replace and should be checked first.
Why Not D (Fuser): The fuser bonds toner to the paper, but it typically causes smudging rather than streaking.
CompTIA A+ Exam Reference: Core 2 (220-1102), Section 4.6, printer troubleshooting.