The best title for this passage is ______.

A．the weight of the hang glider and that of the ultralight airplane
B．ultralight airplanes and military aircraft
C．the inventiveness of John Moody and that of Dctave Chanute
D．the controls used in the Wright brothers' Flyer and those used in today’s ultralight airplanes

A．are inexpensive but difficult to fly
B．are more like go-karts than like hang gliders
C．cannot climb as fast or as high as hang gliders
D．are not too different from the earlier aircraft