Which of the Following Is Not a Difficulty Concerning Beta

Which of the following is not a difficulty concerning beta and its estimation?

A) Sometimes a security or project does not have a past history which can be used as a basis for calculating beta.
B) Sometimes, during a period when the company is undergoing a change such as toward more leverage or riskier assets, the calculated beta will be drastically different than the "true" or "expected future" beta.
C) The beta of an "average share," or "the market," can change over time, sometimes drastically.
D) Sometimes the past data used to calculate beta do not reflect the likely risk of the firm for the future because conditions have changed.
E) All of the above are potentially serious difficulties.