The correct answer is: Beta.
Beta is a measure of the volatility of a security or portfolio in relation to the market. A beta of 1 indicates that the security’s price moves in the same direction as the market, while a beta of less than 1 indicates that the security is less volatile than the market. A beta of greater than 1 indicates that the security is more volatile than the market.
Alpha is a measure of the performance of a security or portfolio relative to a benchmark. A positive alpha indicates that the security or portfolio has outperformed the benchmark, while a negative alpha indicates that it has underperformed the benchmark.
Standard deviation is a measure of the dispersion of a set of data from its mean. A higher standard deviation indicates that the data is more spread out, while a lower standard deviation indicates that the data is more tightly clustered around the mean.
Coefficient of variation is a measure of the relative dispersion of a set of data. It is calculated by dividing the standard deviation by the mean. A higher coefficient of variation indicates that the data is more dispersed relative to its mean, while a lower coefficient of variation indicates that the data is less dispersed relative to its mean.
In conclusion, beta is the best measure of market risk because it measures the volatility of a security or portfolio in relation to the market.