What happens within this code snippet?

def fun$(x)$ :

$($

elif $(x==1)$ :

If you believe that more than one answer applies choose the best answer.

Fibonacci function calculates the $x-$th element.

fun is called but the return value is not stored anywhere.

The function returns $x$ as a binary value.

The function returns $0$ or $1$ based on if it is odd or even.

An error occurs.