The correct option is A 45cm2
Given−ABCDisaparallelogramwitharea=90cm2.EC=DF.ΔBEFsharesbaseEFonthelineFCwiththeparallelogramABCD.AlsotheyarewithinthesameparallelsAB&FC.TofindoutarΔBEF.Solution−WehaveEC=DF∴EC+DE=DE+DF⟹EF=DCi.eThebaseEFofΔBEFandbaseDCofparallelogramABCDareequal.AlsotheyarewithinthesameparallelsAB&FC.∴arBEF=12arABCD⟹arBEF=12×90cm2=45cm2Ans−arBEF=45cm2