What does this function do?

void mystery1(char * clue1, char * clue2) {

while (*clue2++ = *clue1++);

}

a. It copies the contents of the string clue2 to the memory buffer clue1.

b. It copies the contents of the string clue1 to the memory buffer clue2.

c. It does not do anything, because of a compilation failure.

d. It copies the address of string clue1 to the pointer variable clue2.