Problem 4 (20 points) Consider the following skeletal C program: void fun1(void);/* prototype/ void fun2(void);/* prototype / void fun3(void);/* prototype/ void main() f int a, b, c; void fun1(void) int b, c, d; void fun2(void) f int c, d, e void fun3(void) int d, e, f; Given the following calling sequences and assuming that dynamic scoping is used, what va are visible during execution of the last function called? Include with each visible variable the m of the function in which it was defined. riables ame 1. main calls fun1; fun1 calls fun2; fun2 calls fun3. 2. main calls fun1; fun1 calls fun3. 3. main calls fun2; fun2 calls fun3; fun3 calls fun1 4. main calls fun3; fun3 calls fun1. 5. main calls fun1; fun1 calls fun3; fun3 calls fun2