The correct answer is D. variance.
Market risk is the risk that a security will move in the same direction as the overall market. Diversifiable risk is the risk that is specific to a particular security or group of securities. Total risk is the sum of market risk and diversifiable risk.
Sharpe’s alpha is a measure of the performance of a security or portfolio relative to a benchmark. Standard alphas are a set of statistical measures that are used to assess the performance of a security or portfolio. Alpha’s variance is the variance of the alpha of a security or portfolio.
Variance is a measure of the dispersion of a set of data points around their mean. It is calculated by taking the square of the difference between each data point and the mean, and then averaging the squared differences.
In the context of the question, total risk is equivalent to variance because it is a measure of the dispersion of the returns of a security or portfolio around their mean.