Which is a correct declaration and creation of a user$-$defined function in C$++?$

Group of answer choices

void getIt$($int x$)\{$ return x; $\}$

int getIt$($int x$)\{$ return x$*$x; $\}$

void getIt$()\{$ return x; $\}$

string getIt$()\{$ cout $<<5$; $\}$

int getIt$()\{$ cout $<<$ to$\_$string$($x$)$; $\}$