Can someone explain to me how to do these problems please and thanks.

4. Which of the following investors are NOT protected by the limited liability? a. General partners in a limited partnership b. Partners in an LLC c. Stockholders in a S-corporation d. Stockholders in a C-corporation 5. What information is NOT included in a bond certificate? a. Yield to maturity b. Face value c. Coupon rate d. Maturity date 6. Suppose you want to invest for the college expenses of your children, which you estimate to be $200,000. Moreover, you have access to a risk-free savings account that pays an annual interest of 4%, compounded annually. If you anticipate needing the amount in 20 years, how much do you need to invest now in the savings account (You do not plan to withdraw from the account or add more before the 20 years)? a. $75,377.90 b. $84,531.78 c. $91,277.39 d. $110,735.15