The Stock Market of Country a Has an Expected Return

Essay

The stock market of country A has an expected return of 8 percent,and standard deviation of expected return of 5 percent.The stock market of country B has an expected return of 16 percent and standard deviation of expected return of 10 percent.
Assume that the correlation of expected return between A and B is negative 1.
Is it reasonable to conclude that your portfolio is on the efficient frontier? If not,then prove your point by finding just one portfolio weighting between A and B that offers more return with less risk.If you think it is on the efficient frontier,why do you think this?