In a return-standard deviation space, which of the following statements is (are) true for risk-averse investors? (The vertical and horizontal lines are referred to as the expected return-axis and the standard deviation-axis, respectively.) 1) An investor's own indifference curves might intersect. 11) Indifference curves have negative slopes. 111) In a set of indifference curves, the highest offers the greatest utility. IV) Indifference curves of two investors might intersect. A II and III only B I and II only III and IV only D I and IV only E II and IV only