Case-based Critical Thinking QuestionsCase 12-1Casey is using XML to store information about the students in the science classes that he teaches. He wants to design a DTD that he can use to validate the XML documents that he uses for this purpose, and he comes to you for help. Casey next wants to write a declaration for an element named "advanced" that he will use to record the fact that a student is advanced. This element will not contain any content. Which of the following is an appropriate element declaration for this element?

The _______ module performs end-to-end encryption and obtains session keys on behalf of users.

A. PKM B. RCM C. SSM D. CCM

What does the following program do?

``` // What does this program do? #include using namespace std; int mystery( int, int ); // function prototype int main() { int x, y; cout << "Enter two integers: "; cin >> x >> y; cout << "The result is " << mystery( x, y ) << endl; } // end main // Parameter b must be a positive integer to prevent infinite recursion int mystery( int a, int b ) { if ( b == 1 ) // base case return a; else // recursion step return a + mystery( a, b - 1 ); } // end function mystery ```