Only AoA decrease is needed to maintain altitude. Increasing AoB will only maintain the turn rate (or radius of turn), since the question does not state that radius of turn also has to be maintained, AOA REDUCTION will do the job alone!
secondly, assuming that the question implies maintaining both alt and radius, in that case B is the right answer and YES airspeed will increase obviously because you have increased it yourself
the question dosent say that you should not have an increase in airspeed does it? On the contrary, the question states that “ if airspeed is increased”, cuz if there isnt any change in airspeed then why the hell would we be bothering to change aoa and aob and all that jazz!!! common man read the question carefully and answer!