Flow control and congestion control are same at that they all limit the rate of the sender, but differ in that （）.

A.flowcontrollimitsitsratebythesizeofRcvWindow,butcongestioncontrolbythetrafficonthelink
B.congestioncontrollimitsitsratebythesizeofRcvWindow,butflowcontrolbythetrafficonthelink
C.flowcontrolmainlyisaccomplishedbythesender,butcongestioncontrolbythereceiver．
D.flowcontrolmainlyisaccomplishedbythereceiver,butcongestioncontrolbythelink．