The Chief Technology Officer (CTO) of a company, Ann, is putting together a hardware budget for the
next 10 years. She is asking for the average lifespan of each hardware device so that she is able to
calculate when she will have to replace each device. Which of the following categories BEST describes
what she is looking?

A.
ALE

B.
MTTR

C.
MTBF

D.
MTTF