Properties of numerical functions

Which function is odd? Here $x\in \mathbb{R}$.

a) $g(x) = 5$;

b) $h(x) = x^3$;

c) $f(x) = x + 2$;

d) $f(x) = x^3 - 10x$;

e) $f(x) = 2 + x^2 + x$.

Tip: Calculate values of $f(x)$ and $f(-x)$ and compare them.