If n is the number (not the value) of quarters received, then n cannot take values which are fractions and n cannot take negative values. Its values have to be non-negative integers. (Note that 0 is possible.)
That eliminates the descriptions in answers a, b, and c, leaving only answer
d ( 0,1,2,3,...)
as a possibility. Since it describes the non-negative integers, it's the correct one.
it could 14.28 but if its not that one then it has to be the 17 one. hope this ! : )
can you add an image ?