设$D,E,F$分别为$△ABC$的三边$BC,CA,AB$的中点，则$\stackrel{\rightharpoonup }{EB}+\stackrel{\rightharpoonup }{FC}$=

A．

$\stackrel{\rightharpoonup }{AD}$

B．

$\frac{1}{2}\stackrel{\rightharpoonup }{AD}$

C．

$\frac{1}{2}\stackrel{\rightharpoonup }{BC}$

D．

$\stackrel{\rightharpoonup }{BC}$