【单选题】Manypeoplebelievetheglarefromsnowcausessnow-blindness.Yet,darkglassesornot,theyfindthemselvessufferingfromheadachesandwateringeyes,andevensnow-blindness,whenexposedtoseveralhoursof"snowlight".TheUnitedStatesArmyhasnowdeterminedthatglarefromsnowdoesnotcausesnow-blindnessintroopsinasnow-coveredcountry.Rather,aman'seyesfrequentlyfindnothingtofocusoninabroadexpanseofbarrensnow-coveredterrain.Sohisgazecontinuallyshiftsandjumpsbackandforthovertheentirelandscapeinsearchofsomethingtolookat.Findingnothing,hourafterhour,theeyesneverstopsearchingandtheeyeballsbecomesoreandtheeyemusclesache.Natureoffsetsthisirritationbyproducingmoreandfluidwhichcoverstheeyeball.Thefluidcoverstheeyeballinincreasingquantityuntilvisionblurs,thenisobserved,andtheresultistotal,eventhoughtemporary,snow-blindness.ExperimentsledtheArmytoasimplemethodofovercomingthisproblem.Scoutsaheadofamainbodyoftroopsaretrainedtoshakesnowfromevergreenbushes,creatingadottedlineastheycrosscompletelysnow-coveredlandscape.Eventhescoutsthemselvesthrowlightweight,darkcoloredobjectsaheadonwhichtheytoocanfocus.Themenfollowingcanthenseesomething.Theirgazeisarrested.Theireyesfocusonabushandhavingfoundsomethingtosee,stopscouringthesnow-blanketedlandscape.Byfocusingtheirattentionononeobjectatatime,themencancrossthesnowwithoutbecominghopelesslysnow-blindorlost.Inthiswaytheproblemofcrossingasolidwhiteterrainisovercome.?WhentheeyesaresoretearsareproducedtoA、clearthevision
B、remedysnow-blindness
C、easetheirritation
D、loosenthemuscles