Answer:
The correct subjunctive verb for the sentence is were.
Step-by-step explanation:
The mood is the form a verb takes to show how it is to be regarded. The subjunctive mood is the verb form to talk about hypothetical situations or to express a wish, a demand, or a suggestion. In this case, the verb to wish attracts the use of the subjunctive mood. Moreover, as the sentence expresses a wish, was becomes were.