Efficient portfolios of N risky securities are portfolios that Multiple Choice have the lowest standard deviations and the lowest rates of return. have the highest rates of return for a given level of risk. have the highest risk and rates of return and the highest standard deviations. are selected from those securities with the lowest standard deviations regardless of their returns. are formed with the securities that have the highest rates of return regardless of their standard deviations.

Have the highest rates of return for a given level of risk.

Explanation:

Efficient Portfolios offer the highest rates of return for a given level of risk or the lowest risk for a given return. This means that they always maximise returns for a given level of risk which makes them very attractive to the point that they are labeled 'The Optimal Portfolio'.

It is argued at at this level, including any other Investment vehicle or rather diversifying the portfolio further cannot be done unless more risk is accepted. This is the point where the portfolio can get no less riskier for the return it offers.

answer: a. the kind of population living in your neighbourhood.

the census explorer data tool by the us census bureau allows the user to zoom in on any neighbourhood within the united states and find the kind of people residing in that by race and age.  

the tool needs to needs to be used twice – once in order to find what type of people reside in a neighbourhood, and then to see the age groups of the people in the same neighbourhood.