Let h(x) = e−x + kx, where k is any constant. for what value(s) of k does h have the following? (a) no critical points? k < 0 k ≥ 0 k > 0 k ≤ 0 k = 0 (b) exactly one critical point? k ≥ 0 k > 0 k < 0 k ≤ 0 k = 0 (c) a horizontal asymptote?