Final answer:
The streaks on Oliver's printed pages are most likely caused by low ink levels, which is common in inkjet printers after several months of use. Checking and replacing low or empty ink cartridges should resolve the issue.
Step-by-step explanation:
When Oliver, a user in your company, is experiencing streaks on his inkjet printer outputs, the most likely cause of this issue is a) Low ink levels. Inkjet printers often exhibit streaking on the page when ink cartridges are starting to run low. Other potential contributors could include clogged nozzles but this wasn't listed as an option.
To fix the issue, you should start by checking the printer's ink levels and replace any low or empty cartridges. Additionally, most inkjet printers have a built-in utility for cleaning the print head nozzles which can also help if the problem is related to clogged nozzles causing inconsistent ink application.