Which of the following statements is false? a) we say a portfolio is long those stocks that have negative portfolio weights. b) the efficient portfolios are those portfolios offering the highest possible expected return for a given level of volatility. c) when two stocks are perfectly negatively correlated, it becomes possible to hold a portfolio that bears absolutely no risk. d) the lower the correlation of the securities in a portfolio the lower the volatility we can obtain.

Stocks a, b, and c are similar in some respects: each has an expected return of 10% and a standard deviation of 25%. stocks a and b have returns that are independent of one another; i. e., their correlation coefficient, r, equals zero. stocks a and c have returns that are negatively correlated with one another; i. e., r is less than 0. portfolio ab is a portfolio with half of its money invested in stock a and half in stock b. portfolio ac is a portfolio with half of its money invested in stock a and half invested in stock c. which of the following statements is correct? a. portfolio ab has a standard deviation that is greater than 25%.b. portfolio ac has an expected return that is less than 10%.c. portfolio ac has a standard deviation that is less than 25%.d. portfolio ab has a standard deviation that is equal to 25%.e. portfolio ac has an expected return that is greater than 25%.