A Woman Wrenched Her Back Participating in a Limbo Contest

A woman wrenched her back participating in a limbo contest on the weekend. Feeling better, she went to work at her job as a secretary on Monday. Lifting a box of copier paper, she experienced severe back pain and needed immediate medical attention. She was off from work for two weeks due to the injury and filed a claim for workers' compensation. If her employer contested the claim, the most likely outcome of the case would be: ​

A) denial of the claim because the injury did not occur in the course of employment ​
B) denial of the claim because, under the usual exertion rule, the injury did not arise out of employment
C) granting of benefits because, under the usual exertion rule, the injury arose out of employment
D) granting of partial benefits due to the pre-existing injury