One of the Major Reasons That There Is So Little

One of the major reasons that there is so little consensus in practice about which of the four models to use is because

A) financial economics has reached the point where we can provide a theory of expected returns that gives a precise estimate of the cost of capital.
B) financial economics has not yet reached the point where we can provide a theory of realized returns that gives a precise estimate of the cost of capital.
C) financial economics has not yet reached the point where we can provide a theory of expected returns that gives a precise estimate of the cost of capital.
D) financial economics has reached the point where we can provide a theory of realized returns that gives a precise estimate of the cost of capital.