Explanation
The most likely answer is C. Fuser.
A fuser is a component in a laser printer that uses heat and pressure to fuse the toner powder onto the paper. If the fuser is damaged or worn out, it can cause humming and grinding noises, as well as ghost images on the printouts. Ghost images are faint copies of previous images that appear on the same page. They are caused by the fuser not heating the toner properly, or by the toner sticking to the fuser roller and transferring to the next page12.
To fix this problem, you should replace the fuser unit with a new one. You can check your printer manual for instructions on how to remove and install the fuser unit. You can also use a diagnostic ruler to measure the distance between the ghost images and determine if the fuser is the source of the problem2. If the ghost images are far apart (between 4cm and 5cm), then the fuser is likely to be faulty.
References:
1: Solved: "Ghost Images" When Printing - HP Support Community
2: How to Fix Ghosting When Using a Laser Printer and Toner Cartridges - Inksaver