gmat逻辑题
Thepriceofmaplesyruphasjumpedfrom22dollarsthreeyearsagoto40dollarsagallontoday.Itcanbeconcludedthatmaple-syrupharvestershavebeenartificiallyinflatingpricesandthatgovernmentalpriceregulationsarenecessarytocontrolrisingprices.Whichofthefollowing,ifture,caststhemostdoubtontheconclusiondrawnabove?
（A）Thegovernmentalreadyrequiresmaple-syrupharvesterstosubmittheirfacilitiestolicensingbythehealthdepartment.（B）Insectinfestationanddroughthavestuntedthegrowthofsyrupproducingmapletreesandcausedless-abundantsyrupharvests.
（C）Maplesyrupisproducedinruralareasthatsufferfromhighunemployment.
（D）Technologicalimprovementsinmaple-syrupharvestinghavereducedproductioncosts.
（E）Maple-syruppriceshaverisenmanytimesinthepast,thoughneverbeforeattheraterecentlyobserved.