For a Portfolio of 40 Randomly Selected Stocks,which of the Following

For a portfolio of 40 randomly selected stocks,which of the following is most likely to be true?

A) The riskiness of the portfolio is greater than the riskiness of each of the stocks if each was held in isolation.
B) The riskiness of the portfolio is the same as the riskiness of each of the stocks if each was held in isolation.
C) The beta of the portfolio is less than the average of the betas of the individual stocks.
D) The beta of the portfolio is equal to the average of the betas of the individual stocks.