The sentence that contains slang is "Yeah, you know that book was do-pe!". Here option B is correct.
Slang is informal language, often characterized by its use of unconventional words or expressions that are not considered standard in formal communication.
In this sentence, "do-pe" is used as a slang term to mean excellent or impressive. It's a colloquial expression commonly used in informal conversations.
Option A is informal but doesn't contain slang; it simply uses casual language. Option C is also informal, but the words used are standard English, not slang. Therefore, the correct answer is B, as it includes the slang term "do-pe."