HELP PLEASE !!!!!!!!

If the function f(n) models the amount of man-hours it takes to construct (n) televisions that are ready to ship from a electronic manufacturing facility, which describes an appropriate domain for the function?

Aall integers where n ≥ 0
Ball real numbers where n ≥ 0
Call rational numbers where n > 0
Dall rational numbers where n ≥ 0