The answer is neither.
Let's take an odd number and substitute.
- f(3) = 3³ - 4(3)
- f(3) = 27 - 12
- f(3) = 15 (odd)
Now, let's take an even number.
- f(4) = 4³ - 4(4)
- f(4) = 64 - 16
- f(4) = 48 (even)
Since both even and odd numbers are possible, it is neither.