The measure of risk in a Markowitz efficient frontier is

A) specific risk.
B) standard deviation of returns.
C) reinvestment risk.
D) beta.

Markowitz Efficient Frontier

A graphical representation of the most efficient portfolios that provide the best possible return for a given level of risk.

Standard Deviation of Returns

A measure of the volatility of the returns on an investment, indicating the typical deviation from the average return.

Specific Risk

Specific risk is a type of risk that affects a very small number of assets, also known as unsystematic risk, and is associated with factors unique to a particular company or industry.