Points A, B, C, and D are at the corners of a square area in an electric field, with \(\mathrm{B}\) adjacent to \(\mathrm{A}\) and \(\mathrm{C}\) diagonally across from \(A\). The potential difference between \(A\) and \(C\) is the negative of that between \(A\) and \(B\) and twice that between B and D. In terms of the potential difference between \(A\) and \(B\), what is the potential difference

(a) between B and C,

(b) between C and D, and

(c) between A and D?