阅读理解，阅读下面短文，从各题A、B、C、D四个选项中选出最佳答案。

Whichareyoumorelikelytohavewithyouatanygivenmoment-yourcellphoneoryourwallet?Soonyoumaybeabletothrowyourwalletawayandpayforthingswithaquickwaveofyoursmartphoneoveranelectronicscanner．

InJanuaryStarbucksannouncedthatcustomerscouldstartusingtheirphonestobuycoffeein6800ofitsstores．Thisisthefirstpay-by-phonepracticeintheU．S．butwe’relikelytoseemorewirelesspaymentalternativesassomethingcallednearfieldcommunication(NFC)getsintoAmerica'sconsumerelectronics．LastDecembersomenewsmartphoneswhichcontainanNFCchipwereintroducedtothepublic．

AlreadyinuseinpartsofAsiaandEuropeNFCallowsshopperstowavetheirphonesafewinchesaboveapaymentterminal-acontact-freesystembuiltforspeedandconvenience．ButbeforeNFCbecomeswidelyadoptedintheU．S．afewproblemsneedtobeworkedoutlikewhowillgettocollecttheprofitabletransaction(交易)fees．Althoughsomecreditcardprovidershavebeenexperimentingwithwave-and-paysystemsthatuseNFC-enabledcreditcardscellphoneserviceprovidersmaytrytomuscletheirwayintothepoint-of-sale(POS)market．Threebigcellphoneserviceprovidershaveformedajointventure(合资企业)thatwillgointooperationoverthenext15months．Itsgoalis“toleadtheU．S．paymentsindustryfromcardstomobilephone．”

TheotherbigNFCissueapartfromhowpaymentswillbeprocessedissecurity．Forinstancewhat'stostopathieffromdigitallypick-pocketingyou?“We’restillnotatthepointwhereanattackercanjustbrushagainstyouinacrowdandstealallthemoneyoutofyourphone”saysJimmyShah．Amobile-securityresearcher“Usersmayalsobeabletosettransactionlimitsperhapsrequiringapasswordtobeenteredforlargerpurchases．”

Stilluneasyaboutthisdigital-walletbusiness?Keepinmindthatifyouloseyoursmartphoneitcanbelocatedonamapandremotelydisabled．Plusyourphonecanbepasswordprotected．Yourwalletisn't．