Which reason can cause a laser printer to produce prints with irregular spots?

A dirty drum can lead to prints with irregular spots because the drum is a critical component in the printing process. In a laser printer, the drum is responsible for transferring the toner onto the paper. Over time, dust, toner residue, or other contaminants can accumulate on the drum’s surface. When this happens, the toner may not adhere evenly or might transfer inconsistently, resulting in dark spots, specks, or streaks on the printed document. Keeping the drum clean is essential for maintaining print quality.

While other factors like a defective printer driver could cause printing issues, they would more likely lead to problems such as incorrect formatting or driver-related errors rather than irregular spots on the print. Similarly, incorrect paper size could create issues such as paper jams or misalignment but would not typically cause spotting, and a faulty toner cartridge could lead to a range of printing problems, such as faded prints or streaks but not specifically irregular spots unless the cartridge is significantly malfunctioning. Thus, the cleanliness of the drum is directly linked to the type of print defects described in the question.