We have three commodities: xylophones (x), yaks (y) and zebras (z) The beta of x against y is -0.5 and the beta of y against z is 0.2. Which of the following are necessarily true, necessarily false, or could be either true or false: (a) When the price of xylophones goes up, the price of yaks typically goes down. (b) The volatility of yaks is less than that of zebras. (c) Knowing that the price of yaks went up by 1 percent in the last quarter, you would expect (given no other information) that the price of zebras went up by 5 percent. (d) Holding a portfolio of xyplophones and yaks is less risky than holding a portfolio of xylophones and zebras. (e) Knowing that the price of yaks went up by 5 percent in the last quarter, you would expect (given no other information) that the price of zebras went up by 1 percent