Usually, when you talk to your friends, you don't follow every grammar rule in the book. This is why spoken English is far more informal and flexible, giving room to slang. In the same way, with the exception of the first example, all the other sentences follow conventional Standard English grammatical rules. Only the first sentence shows a more conversational syntax (word order) being used. Therefore, the best answer is A.
On that note, we could infer that the first example sounds like how British speak, as they are known for their frequent use of tag questions.