Suppose that stocks are exposed to independent risks only so that stock i has the following return structure: Ri,t=mi+ei,t where mi is the average return, and ei,t is the independent risk. When we construct a portfolio including more and more stocks, which of the following would happen? The portfolio volatility gradually decreases and eventually converges to a certain positive value. The portfolio volatility gradually decreases and eventually converges to zero. The portfolio volatility stays unchanged