Consider a recursive function decToBin $($decimal$)$ that converts a decimal number to a binary representation but still in base $10.$ Note that all inputs and output are $32-$bit integers.

Example outputs:

decToBin$(7)=111($one hundred and eleven$)$

decToBin$(23)=10111($ten thousand, one hundred and eleven$)$

decToBin$(18)=10010($ten thousand and ten$)$

What is the time complexity of decToBin?

$O(logn)$

None of the other answers are correct

$O(1)$

o$(($:$2^n$