$82)$ According to Markowitz portfolio theory:A$)$ adding a risky stock to a $($less risky$)$ bond portfolio can decrease portfoliorisk.B$)$ a portfolio with the minimum risk for its level of expected return lies on theefficient frontier.C$)$ combining any two risky assets in a portfolio will reduce unsystematic riskcompared to a portfolio holding only one of the two risky assets.D$)$ none of the above