Answer whether each of the following statements is correct and explain your argument.

(a) Under an index model, the correlation between two individual stocks is one.

(b) Well-diversified portfolios with a negative are under-priced.

(c) An arbitrage portfolio arises when two or more security prices enable investors to construct a portfolio that will yield a positive return under all possible scenarios.

(d) A well-diversified portfolio eliminates all risks.