which of the following statements describes and unsystematic risk?

I. also known as diversifiable risk, is the practice of investing in a variety oif diverse assets as a mean of reducing risk

II$.$ also known as risk premium, is the excess return with respect to the risk free rate

III. also known as the overall risk, uniqeue risk and market risk: it is measured by the standard deviaton of returns

IV$.$ also known as market risk, is the risk that affects a large number of assets or the entire market, measured by beta

V$.$ also knoiwn as unique of asset specific risk, is the risk that affects an individual security or a small number of securities