Group actions — Burnside's count of orbits

Let $X=\{1,…,17\}$ and $S_{17}$ be the group of permutations of $X$. For a subgroup $G$ of $S_{17}$ and $x\in X$, let $S_G(x)=\{\sigma\in G\mid\sigma(x)=x\}$. Which of the following statements is true for every subgroup $G$ of $S_{17}$?