Sentence B is the correct option. When using "however" to write a compound sentence, we should write a semi-colon before and a comma after it. When "however" is used at the beginning of a sentence, we should write a comma following it.
I find all of the answers pretty neutral (that is, giving only facts, no judgements) except on sentence 3: this is because of the word "sharply".
It seems that the author of this sentence makes a judgement about the split: that they're very split, that their argument was very intense. It seems like a judgement to me more than the other sentences.
