∵DE⊥BC，DF⊥AB，∴∠EDC=∠EDB=∠DFB=90°，又∵∠B=∠C，∴∠FDB=∠DEC，∵∠AED=160°，∴∠FDB=∠DEC=20°，∴∠EDF=90°-∠FDB=70°．故选C．
