I Have 3 Possible Choices for a Lawnmower

Multiple Choice

I have 3 possible choices for a lawnmower. They have expected working lives of 3, 4 and 5 years. If I expect lawnmower technologies to be stable for the foreseeable future, over what period of time should I compare the equivalent uniform annual costs of the three choices?

A) 12 years
B) 20 years
C) 30 years
D) 45 years
E) 60 years