where the spouses are habitually resident at the time the court is seized; or, failing that
(b)
where the spouses were last habitually resident, provided that the period of residence did not end more than 1 year before the court was seized, in so far as one of the spouses still resides in that State at the time the court is seized; or, failing that
(c)
of which both spouses are nationals at the time the court is seized; or, failing that