单选题：CUncleSamisatall，thinman.He‘sanoldermanwithwhitehairandawhit

C
UncleSamisatall，thinman.He‘sanoldermanwithwhitehairandawhitebeard.Heoftenwearsatallhat，abowtie，andthestarsandstripesoftheAmericanflag.
Whoisthisstrange，lookingman?WouldyoubelievethatUncleSamistheUSgovernment?ButwhydoyoucalltheUSgovernmentUncleSam?
DuringtheWarof1812，theUSgovernmenthiredmeatpackerstoprovidemeattothearmy.OneofthesemeatpackerswasamannamedSamuelWilson.Samuelwasafriendlyandfairman.EveryonelikedhimandcalledhimUncleSam.
SamWilsonstampedtheboxesofmeatforthearmywithalargeUSforUnitedStates.SomegovernmentinspectorscametolookoverSam‘scompany.TheyaskedaworkerwhattheUSontheboxesstoodfor.Asajoke，theworkeransweredthattheselettersstoodforthenameofhisboss，UncleSam.
Thejokespread，andsoldiersbegansayingthattheirfoodcamefromUncleSam.Beforelong，peoplecalledallthingsthatcamefromthegovernment“UncleSam‘s”，“UncleSam”becameanicknamefortheUSgovernment.
SoonthereweredrawingsandcartoonsofUncleSaminnewspapers.Intheseearlypictures，UncleSamwasayoungman.Heworestarsandstripes，buthishairwasdarkandhehadnotabeard.ThebeardwasaddedwhenAbrahamLincolnwasPresident.PresidentLincolnhadabeard.
ThemostfamouspictureofUncleSamisonaposterfromWorldWarI.Thegovernmentneededmentofightinthewar.Intheposter，averyseriousUncleSampointshisfingerandsays“IwantYOUfortheUSArmy.”
“UncleSam”becamea________fortheUSgovernment.
A.boss
B.nickname
C.picture
D.businessmen