What is the output of the following code given the function definition below?

string word = “Hello”;
mystery (word);
cout << word;

void mystery (string &p) // function definition
{
int size = p.length ();
for (int c = 0; c < size; c++)
p.insert(0, “*”);
}

a) Hello
b) *Hello
c) Hello*****
d) *****Hello

d) *****Hello