PTE Fill in the blanks R/W 8.Graphene

Fascination with this material stems from its remarkable physical properties and the potential applications these properties offer for the future. __________ scientists knew one atom thick, two dimensional crystal graphene existed, no-one ___________ out how to extract it from graphite. That was until it was isolated in 2004 by two researchers at The University of Manchester, Professor Andre Geim and Professor Kostya Novoselov. This is the story of how that stunning scientific feat came about and why Andre and Kostya won the Nobel Prize in Physics for their pioneering work. Andre and Kostya frequently held ‘Friday night experiments’ – sessions where they would try out experimental science that wasn’t ___________ linked to their day jobs.
Options:
1) Since, Unless, However, Although
2) had worked, works, working, work
3) necessarily, fully, solely, indirectly