2. Given the following calling sequences and assuming that dynamic scoping is used, what variables are visible during execution of the last function called? Include each visible variable name of the function in which it was defined. a) main calls fun1; fun1 calls fun2; fun2 calls fun3 b) main calls fun2; fun2 calls fun3; fun3 calls fun1 c) main calls fun1; fun1 calls fun3; fun3 calls fun2 void funl (void) { int b, c, d; 1 void fun2 (void) { int c, d, e; 1 void fun 3 (void) { int d, e, f; } void main() { int a, b, c; }