What will be the output of the following code?

#include <iostream>
#include <string>
using namespace std;
void func1(string input,string output)
{
    if(input.length()==0)
    {
        cout<<output<<",";
        return;
    }
    for(int i=0;i<=output.length();i++)
    func1(input.substr(1),output.substr(0,i) + input[0] + output.substr(i));
}
 
int main()
{
    char str[] = "AB";
 
	func1(str, "");
    return 0;
}

A. AA,BA,

B. AB,BA,

C. BA,AB,

D. AB,AB,

Answer: Option C