Which of the following code snippets converts the integer $n$ to a string s$?$

ostringstream strm; string $s$; strm $$ n; $s=strm.str()$;

istringstream strm; string $s$; strm $sstrm.str(n)s$;

ostringstream $strm$; string $s$; $strm.str(n)$; $strs$;