Given the following code:

def subtract$\_$one$($num$)$:

num $=$ num $-1$

print$(\text{'}$inside function: $\text{'}+$ str$($num$))$

print$(\text{'}$before function call: $\text{'}+$ str$($val$))$

subtract$\_$one$($val$)$

print$(\text{'}$after function call: $\text{'}+$ str$($val$))$

The code will print out:

before function call: $9$

inside function: $8$

after function call: $9$

Why does the value of val not become $8$ after the function call? Select all that apply.

The variable val is a global variable and cannot be changed inside a function.

Changing the parameter num inside the function does not change the value of val outside the function.

The function subtract$\_$one should return num, and it should be assigned back to val.

The parameter num should be declared as global inside the function.