D.. I think. Although it's long, it best expresses the meaning of the two sentences it combined.
Answer: The problem that is illustrated by the sentence provided is "grammatically incorrect".
Explanation: The sentence "I joined the others by the fire however they were about to go to bed" is grammatically incorrect because it contains punctuation mistakes. The sentence provided includes a connector ("however") that is joining two independent clauses<u>. Punctuation rules state that a semicolon must always be added before "however" and that a comma must always come after it</u>. In that way, <u>as the sentence provided does not include a semicolon nor a comma, the sentence is grammatically incorrect.</u> The correct way of writing it is: "I joined the others by the fire; however, they were about to go to bed".
