The four options for the first blank are all conjunctions. They're used to link clauses, sentences... together. So I can't give you a correct choice because I don't know what the context is.
" as you continue to wait patiently for your boarding call " - I think "as" in this clause means "because".
Although the plane is the fastest means of transport, the idea of travelling by plane does not appeal to everyone because of the frequent delays. It is extremely ….(1)…. when you allow yourself ….(2)…. time to get to the airport and, once there, it is brought to your attention that there is a problem with your flight. The staff at the check-i