This code is executed using Python Tutor: \[ \begin{array}{l} \text { def add_one }(x) \text { : } \\ x=x+1 \\ \text { return } x \\ x= 0 \\ y= \text { add_one }(3) \end{array} \] How many variables named x and y appear in the memory model just before the return statement is executed? One variable named x and one variable named y. Two variables named x and zero variables named y. Two variables named x and one variable named y. One variable named x and zero variables named y