Correct Answer : Option (B) :   Flap
                                                                                                                
                                                                                                                                                                        
                                                        Explanation : Flap is a high lift device. Flap is used to increase lift produced by the wing. Flaps are used to increase camber and overall surface area of the wing. This results in increased lift. Dutch roll, phugoid, lateral mode etc. are typical aircraft dynamic modes.