Take another look at the sentence:
Christine wrang her hands as she listened to Dr. Armour's lecture about tardiness. Although Christine swore to her math teacher that she would never be late again, everyone in the class knew that when the alarm clock rang the next morning, Christine would hit the snooze button one time too many.
The first verb, wrang, is the problem. The sentence requires the simple past. Wrung is the correctly spelled form.
|Verb||Simple Present||Simple Past||Past Participle|
Rang, the verb you chose, is perfectly correct. Before you continue, review the rules for irregular verbs.