The correct answer to this question would be option B, i.e. 'were' as the sentence exemplifies a subjunctive mood that describes a wish. Apart from other uses of the verb in the subjunctive mood(to describe unfactual or doubtful situations), it is also used to describe a hypothetical situation, wish or request. Since the sentence exemplifies a wish, thus, the correct form of the verb that should be used is "were".
