The correct answer is: C. historical betas
Historical betas are calculated using historical data on a security’s returns and the returns of the market portfolio. As time passes, historical betas tend to move towards 1.0 because the security’s returns become more correlated with the returns of the market portfolio.
Standard betas are betas that are calculated using a standardized methodology. This methodology typically involves using a market index as the proxy for the market portfolio. Standard betas are often used in financial models and analyses.
Varied betas are betas that are calculated using a variety of different methodologies. This can include using different market indices as the proxy for the market portfolio, or using different time periods to calculate the beta. Varied betas are often used to get a more accurate picture of a security’s risk profile.
Adjusted betas are betas that have been adjusted for certain factors, such as changes in the market or the security’s risk profile. Adjusted betas are often used to get a more accurate picture of a security’s risk profile in the current environment.