The correct option is
B Quills
A) Contour feathers are small feathers that give the body shape.
B) Quill feathers are large feathers found in the wings and tail that help in flight.
C) Coverts are small feathers found in the wings and tail that fill up any gaps between quill feathers.
D) Filoplumes occur under contour feathers.
So the correct answer is 'Quills'.