## mappings

Let $\alpha$ be a map transpositions to transpositions. If $x \in S_n$ then $i_x \in Aut(S_n)$ maps transpositions to transpositions.

Show that the set of $\alpha \in Aut(S_n)$ which maps transpositions to transpositions is a subgroup of $Aut(S_n)$.

Help this to prove.