17. Alpha and Beta are inhabitants of an island of knights and knaves, where knights always tell the truth and knaves always lie. Alpha and Beta are alone at a beach when Alpha says: "At least one of us is a knave." And Beta says: "We are both knaves." Which of the following is/are true?\\
(a) Alpha and Beta are both knights\\
(b) Alpha and Beta are both knaves\\
(c) Alpha is a knight and Beta is a knave\\
(d) Alpha is a knave and Beta is a knight

\section*{Questions 18 to 20 are based on the following code.}
The two arguments to the function Mystery(A, n) in the code below are: (i) an integer array A indexed from 0 , and (ii) the number n of elements in A . Each element of A is an integer from the set $\{ 1,2 , \ldots , n \}$. The expression [0] $* ( \mathrm { n } + 1 )$ creates an array, indexed from 0 , that contains $n + 1$ zeroes.

\begin{verbatim}
function Mystery(A, n) {
    found = False;
    value = None;
    B = [0] * (n+1);
    for i from 1 to n {
        B[A[i]] = B[A[i]] + 1;
    }
    for i from 1 to n {
        if (found == False) {
            if (B[A[i]] == 1) {
                found = True;
                value = A[i];
            }
        }
    }
    if (found == True) {
        return(value);
    } else {
        return(None);
    }
}
\end{verbatim}

Answer the next three questions about this function.\\[0pt]