What will be the value of the variable list$2$ after the following code executes?

$$ list$1=[1,2,3]$

$$ list$2=[]$

$$ for element in list$1$:

$$ list$2.$append$($element$)$

$$ list$1=[4,5,6]$

$$

Group of answer choices

$[1,2,3]$

$[4,5,6]$

$[1,2,3,4,5,6]$

Nothing; this code is invalid

$$