whether 와 to 부정사

The company’s final decision on whether or not _______ Ms. Jason is contingent on the result of a reference check by human resources.( ~ 에 따른.)

 (A) hire 

 (B) hiring 

 (C) to hire  

 (D) will hire

contingent on : ~ 에 달려있는

The company's final decision on whether it will hire Ms. Jason ( or not ) is contingent on
The company's final decision on whether to hire Ms. Jason ( or not ) is contingent on
The company's final decision on whether or not to hire Ms. Jason ( or not ) is contingent on