The classification of speech varieties as dialects or languages and their relationship to other varieties of speech can be controversial and the verdicts inconsistent. English and Serbo-Croatian illustrate the point. English and Serbo-Croatian each have two major variants (British and American English, and Serbian and Croatian, respectively), along with numerous other varieties. For political reasons, analyzing these varieties as "languages" or "dialects" yields inconsistent results: British and American English, spoken by close political and military allies, are almost universally regarded as dialects of a single language, whereas the standard languages of Serbia and Croatia, which differ from each other to a similar extent as the dialects of English, are being treated by some linguists from the region as distinct languages, largely because the two countries oscillate from being brotherly to being bitter enemies. (The Serbo-Croatian language article deals with this topic much more fully.)
Serbian and American English are the major variants of which language?