Which of the following is an example of subjunctive verb mood

1) I am happy.

2) If I were a millionaire, I would buy a mansion.
3) She dances well.

The correct answer is:
2) If I were a millionaire, I would buy a mansion.

One example of the subjunctive verb mood is "wish".

The sentence "I wish I were taller" is an example of the subjunctive verb mood. The use of "were" instead of "was" in this sentence reflects the hypothetical or contrary-to-fact nature of the speaker's wish. In the subjunctive mood, we use the base form of the verb ("be") instead of the past tense form ("was").