Need help explaining this pls

(6) What is risk? Although many risks (e.g., career risk, risk of how many children to have and whether they will succeed morally and academically, etc.) in the real world are not tradable, some risks (e.g., stock price risk, credit risk, interest rate risk, currency exchange rate risk, risks that insurance policies cover, etc.) are actively traded in the market. What determines the equilibrium price of tradable risks? (20%; your answer to this question should not exceed one page) (7) What is opportunity cost? As scarce resource, financial capital has an opportunity cost. What determines the opportunity cost of capital? (10%; your answer to this question should not exceed one page) (8) Both stock and bond returns are based on the cash flows generated by the issuing firm. How do shareholders and bondholders differ in their claims of the firm's cash flows? How do such claim differences cause the risk difference between stocks and bonds? (10%; your answer to this question should not exceed one page)