Hi what does the prefix un mean

Which statement best paraphrases these sentences from the text

While looking at ads on a professional job site, justin saw this job posting: "the employee should have a degree in human behavior and at least 5 years experience in behavioral modifications. we are also looking for an employee who is good at crisis divergence. typically employees will spend a lot of time supporting others."

Boss: oh no! that’s the phone again! secretary: blank boss: . a. shall i take it? b. will you answer it? c. can you do me a favor? d. may i hang it up?