Here is the item:
Because Tran knew that a strong chemistry background was essential for a future pharmacist, she rose from her warm bed and begun studying her notes for another test.

The third verb, begun, is incorrect. As you know, this sentence requires the simple past. Began is the right form.

Verb Simple
Present
Simple
Past
Past
Participle
begin begin(s) began begun

Go to the next item, champ!