ACCorDing to thE pAssAgE, thE AmEriCAn rEstAurAnt wAitEr mAy proviDE morE sErviCE thAn rEquirED mAinly BECAusE______.
A．thE AmEriCAn EmployErs DEmAnD ExtrA working hours For thEir workErs
B．thE AmEriCAn wAitErs DEpEnD grEAtly on tips From CustomErs
C．it's A Custom oF thE AmEriCAn soCiEty
D．thE AmEriCAn wAitErs BEliEvE thAt CustomEr is AlwAys right