The subjunctive mood is a way of talking about unreal or conditional situations. It is also used to describe desires, wishes, needs, or intentions. To indicate the subjunctive mood, the verb, 'were' is used instead of 'was', along with singular as well as plural nouns. Hence, the appropriate verb is 'were', as given in option B.The use of the phrase, 'was been' and 'were been' is grammatically incorrect as the word, 'been' is used along with the auxiliaries, 'have', 'has' and 'had'. It is never used with 'was' and 'were'. Hence options A and C are incorrect.
Option D is incorrect as option B is correct.