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

Question $5$ options:

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

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

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

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