Please double check my logic and explain:

On September 1, 2022, LSUS Magazine sold 100 one-year subscriptions for $120 each. The total amount received was credited to Unearned Revenue. What would be the required adjusting entry at December 31, 2022?

=100*120 = 12000

1. Debit service revenue by $2,000, credit unearned revenue by $2,000
2. Debit service revenue by $4,000, credit unearned revenue by $4,000
3. Debit unearned revenue by $4,000, credit service revenue by $4,000
4. Debit unearned revenue by $12,000, credit service revenue by $12,000