The Bishop.
In this position three Bishops are on the board, c3, c4, f6; also three Rooks, c1, d2, f7, and of course the two Kings - the Kings never being captured - on a1 and g8. Since the Bishops move diagonally, Bishop C3 can capture f6, and vice versa. But the Bishop c3 cannot capture Rook d2 because the Bishop is forced to protect its King against Bishop f6 by obstruction. The Bishop c4 can capture Rook f7; this piece is immobile since it is pinned by the Bishop c4. The number of squares to which in the above position the Bishops might move, is therefore found to be for c4 = 10 to (a2, b3, d5, e6, f7, b5, a6 d3, e2, f1); for f6 = 9 (h8, g7, e5, d4, c3, e7, d8, g5, h4); for c3 = 4 (h2, d4, e5, f6).