Linguist: Regional dialects, many of which eventually become distinct languages, are responses by local populations to their own particular communicative needs. So even when the unification of the world economy forces the adoption of a universal language for use in international trade, this language itself will inevitably develop many regional dialects. Which one of the following is an assumption that the linguist's argument requires? ['A universal language for use in international trade will not arise unless the world economy is unified.', 'After the unification of the world economy, there will be variation among many different local populations in their communicative needs in international trade.', 'No two local populations have the same communicative needs as each other.', 'When the unification of the world economy forces the adoption of a universal language for use in international trade, many regional dialects of other languages will be eradicated.']