The correct option is B We have to go to New Jersey by airplane as we cannot go there any other way.
From the given options, we can analyse the order of the connected sentences and logic to pick the right answer. In option A 'so' is used as a connector expressing a consequence but in using 'so', the coordinated clause of consequence must follow the main clause. So, option A is incorrect. 'so that' is generally used before the clause which indicates the purpose, so the sentence construction in option C is incorrect. 'although' is used to mean 'however or 'but'. So, option D is not appropriate. Since 'as' is used to connect the result of something with its reason, thus option B is appropriate.