A copper mining companys stock is expected to have a 6% return, and a volatility of 60%. A public utility companys stock, perfectly negatively correlated with the copper mining companys stock, has 6.5% expected return and a volatility of 15%. Based on the above information, what should be the risk-free rate in a no-arbitrage (normal) capital market? a) 5% b) 6.4% c) 7% d) 8% e) None of the above