by diversifying, the risk of holding stock a. can be reduced but not eliminated. on average over the past two centuries stocks paid a higher average real return than bonds. b. can be reduced but not eliminated. on average over the past two centuries stocks paid a lower average real return than bonds. c. can be eliminated. on average over the past two centuries stocks paid a lower average real return than bonds. d. can be eliminated. on average over the past two centuries stocks paid a higher average real return than bonds.