Let f be a mapping from x = {1, 2, 3, ......., 50} to itself such that for m, n
x, m - n implies that f(m) - f(n). then which of the following is true

Let f be a mapping from X = {1, 2, 3, ......., 50} to itself such that for m, n
X, m - n implies that f(m) - f(n). Then which of the following is true ? (A) There is m
X such that f(m) = m (B) For every m
X, we may have f(m) = m – 1 (C) For every m
X, we may have f(m) = m + 1 (D) For every even m
X, we must have f(m) = 1/2 m