Which of these is not an issue?

a.The beta used in CAPM does not have a standard method of calculation; there could be many different beta values for the same stock

b.If the risk-free rate increases to a level greater than expected market return, the cost of equity becomes lower than the risk-free rate.

c.The difference between the cost of equity among companies depends solely on the company's beta.

CAPM produces only an estimate of the cost of equity.