With Regard to the Benefits of Diversification, Nominate the Incorrect

With regard to the benefits of diversification, nominate the incorrect statement:

A) The expected (mean) return for the portfolio lies between the highest return for all assets in the portfolio and the lowest return for all assets in the portfolio.
B) The riskiness of a portfolio is simply a weighted average of the standard deviations of the individual shares in the portfolio.
C) Portfolio risk can be reduced to close to zero when the returns of the shares contained in the portfolio are perfectly negatively correlated, that is they have a correlation coefficient of -1.0.
D) A correlation coefficient of -1 would indicate that the two companies move counter-cyclically to each other.