Which one of the following words from passage means 'come to be known'?

The word 'transpire' means 'to come to be known' or 'to become apparent.' In the passage, the sentence 'Only after a considerable period of contact does it transpire that the speech is so different...' uses 'transpire' precisely in this sense. Lingua franca refers to a common language used between speakers of different languages, straight means direct, and variant refers to a different form, none of which match the meaning 'come to be known.'