【单选题】Initial stall tests and other dynamic maneuvers have been run, as well as an extensive check-out of the airplane's systems. stall test means:
A.
a table or a small shop with an open front, especially outdoors, where goods are sold
B.
a section inside a farm building that is large enough for one animal to be kept in
C.
a small area in a room, surrounded by glass, walls, etc., that contains a shower or toilet
D.
a situation in which an aircraft loses speed and goes steeply downwards