4 a. The current price of RIO stock is $25 per share. If RIO's current dividend is $1 per share and investors' required rate of return is 10 percent, wha is the expected growth rate of dividends for RIO, based on the constant growth dividend valuation model? (2 marks) b. Using diagram(s) describe non-diversifiable and diversifiable risk. (3 marks) c. What is the efficient market hypothesis? Discuss the three forms of the efficient market hypothesis. (2+3-5 marks)