It dosn't matter if it is level flight or not sends clown.
You can be climbing or decending the only thing that will change is the max speed obtained.
Alex
Since you say configuration isn't mentioned so we can discount it. In that case we can discount the dirty side of the drag curve and presume S & L
But how can you decrease the drag of a clean aircraft flying at its max thrust at constant speed in straight and level flight?
MJ