If the computer in office 3 was bought in 1988, then which one of the following statements could be true?

I am still confused as to why the printer for office #2 HAS TO BE 89? I know that the computer has to be 89 for office #2 because the computer for office #3 is 88 and they cannot be the same year. I don't see the forcibly action of making the printer in office #2 89....