Risk and Return. Suppose that the risk premium on stocks and other securities did, in fact, rise with total risk (i.e., the variability of returns) rather than just market risk. Explain how investors could exploit the situation to create portfolios with high expected rates of return but low levels of risk. (LO12-2)

Diversification could never eradicate the systematic risk. It's indeed primarily even though all securities shift somewhat in unison (a significant part of their volatility is purposeful) also that diversified stock strategies remain volatile. Additionally, if I am a thing that separates by purchasing a proportion throughout the S & P indicator, I would also have indeed very variable returns because the global economy as a whole has been fluctuating widely.
The unsystematic risk seems to be the volatility in share markets arising through factors unique to something like an individual's abilities. The risk involved with this kind of volatility is essentially the form whereby diversification could increasing.
The entire premise of portfolio selection would be that, to both the degree that shares don't shift in unison all of the occasions, variations throughout the performance from every other given sector appear to have been wiped clean or softened out by additional differences in contributions from several other investments.