A complete traversal of an $\backslash ($ n $\backslash )-$node binary tree is a$($n$)\_\_\_\_\_\_\_\_\_$ operation if visiting a node is $\backslash ($ O$(1)\backslash )$ for the iterative implementation.

Question $1$ options:

$\backslash ($ O$($n$^2)\backslash )$

$\backslash ($ O$($n$)\backslash )$

$\backslash ($ O$(1)\backslash )$

$\backslash ($ O$(\backslash$log$\_2$ n$)\backslash )$