JEE Math Practice Question

Let $$A = \{ 1,2,3,....,10\} $$ and $$f:A \to A$$ be defined as $$f(k) = \left\{ {\begin{matrix} {k + 1} & {if\,k\,is\,odd} \\ k & {if\,k\,is\,even} \\ \end{matrix} } \right.$$ Then the number of possible functions $$g:A \to A$$ such that $$gof = f$$ is :

1. A.55
2. B.105
3. C.5!
4. D.10C5