Answer:
Yes, there is an opportunity.
Explanation:
Beta is an indicator of the risk of any portfolio. The higher beta, the greater the risk. Therefore, the expected return of that portfolio should be higher.
Portfolio B has a higher Beta than portfolio A, but a lower expected return, so we say that the portfolio B is more expensive than it's value. So, there is an opportunity for arbitrage. You should sell the protfolio B and buy the portfolio A, and win the difference between both operations, with no risk.
