题目内容：
根据以下材料回答题 Itisoftendifficultforamantobequitesurewhattaxheoughttopaytothegovernmentbe-causeitdependsonsomanydifferentthings:whetherthemanismarried;howmanychildrenhehas;whetherhesupportsanyrelations;howmuchheearns;howmuchinteresthereceives;howmuchhehasspentonhishouseduringtheyear,andsoonandsoforth．Allthismakesitdifficulttodecideexactlyhowmuchthetaxis．
Therewasacertainartistwhowasalwaysverycarefultopaytheproperamount．
Oneyear,afterpostinghischeckasusual,hebegantowonderifhehadpaidenough,andaf-teralotofwork,withapencilandpaper,hedecidedthathehadnot．Hebelievedthatheowedthegovernmentsomething．
Hewasjustwritinganotherchecktosendtothetax-collectorwhenthepostmandroppedalet-terintotheboxatthefrontdoor．Openingit,theartistwassurprisedtofindinsideitacheckforfivepoundsfromthetax-collector．Theofficialexplainedthattoomuchhadbeenpaid,andthatthereforethedifferencewasnowreturnedtothetaxpayer．
Itismentionedinthepassagethatonehastopaytaxaccordingto__________． A．howmucheducationonehasreceived
B．whetheroneissingleormarried
C．howoldone'schildrenare
D．whereonelives
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答案解析：