The board follows policy that is unreasonably strict and so inflexible that <they refuse to discuss permitting leaves of absences even when justifiable.>

1. they refuse to discuss permitting leaves of absences even when justifiable.
2.it refuses to discuss permitting leaves of absences even when it is
3.it refuses to discuss permitting leaves of absences to be taken even when they are
4.permitting leaves of absences is not discussed even when
5.discussion of permitting leaves of absences is refused even when they will be

I understand that the first subject is the Board-singular, but what about permitting leaves of absences?? Is it a singular subject or Plural. and how should I decide it?