I'm having trouble understanding this question. Can anyone help?

If n and y are positive integers and 450y=n^3 which of the following might be an integer

I. y/3x2^2x5

II. y/3^2x2x5

III. y/3x2x5^2

None
I only
II only
III only
I, II, and III

the answer is I only.

Thanks