TheAPIchangesshouldprovidebothsourceandbinary(_______)forprogramswrittentotheoriginalAPI.Thatis,existingprogrambinariesshouldcontinuetooperatewhenrunonasystemsupportingthenewAPI.Inaddition,existing()thatarere-compiledandrunonasystemsupportingthenewAPIshouldcontinuetooperate.Simplyput,theAP(I)formulticastreceiversthatspecifysourcefiltersshouldnotbreakexistingprograms.ThechangestotheAPIshouldbeassmallaspossibleinordertosimplicitythetaskofconvertingexisting()receiverapplicationstousesourcefilters.Applicationsshouldbeabletodeletewhenthenew()filterAPIsareunavailable(e.g.,callsfailwiththeENOTSUPPerror)andreactgracefully(e.g.,reverttooldnon-source-filterAPIordisplayameaningfulerrormessagetotheuser). 横线处应选()。
A.capability
B.compatibility
C.labiality
D.reliability
正确答案是B