CAPM has become one of the most important concepts in Finance because of these reasons except:

I. It builds upon the Markowitz risk$-$return framework by defining the relationship between the two.

II$.$ It defines the role of taxation and transaction costs in investment returns when trading equities

III. It provides a $$benchmark$$ rate of return to employ when evaluating investment alternatives.

IV$.$ It provides a means to estimate a firm$$s cost of capital.

I. All are reasons.

II$.$ Only I and IV are reasons.

III. Only I, II and III are reasons.

IV$.$ Only II is not a reason.

V$.$ Only III is not a reason