please answer all three parts. i got the last question wrong

Standard deviation of the portfolio with stock A is 6. (Round to two decimal places.) Standard deviation of the portfolio with stock B is \%. (Round to two decimal places.) Which stock should you add and why? (Select the best choice below.) A. Add A since the portfolio is less risky when A is added. B. Add B because the portfolio is less risky when B is added. C. Add either one because both portfolios are equally risky. You have a portfolio with a standard deviation of 26% and an expected return of 18%. You are considering adding one of the two stocks in the following table. If after adding the stock you will have 30% of your money in the new stock and 70% of your money in your existing portfolio, which one should you add