B. Language
"You are listening to a recorded conversation between two persons, but they use very colloquial words that British-English speakers use." For me, this is relating to language.
This is language because the two person are speaking in an informal language where British-English speakers use it. It is not about the amount of information because there is no information available and they were only having a conversation. It is not also about the speed and length as there is no speed and length focused in the situation.
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