[单选题]The measure of risk in a Markowitz efficient frontier is ()adQ答案窝(daanwo.com)-大学生作业答案及考资分享平台 Aspecific risk.adQ答案窝(daanwo.com)-大学生作业答案及考资分享平台 Bstandard deviation of returns.adQ答案窝(daanwo.com)-大学生作业答案及考资分享平台 Creinvestment risk.adQ答案窝(daanwo.com)-大学生作业答案及考资分享平台 Dbeta.