These are two different sentences and you already mentioned that the origional sentence had a comma splice, so option 1 is incorrect. A semicolin can always be used for joining two complete sentences, so option 2 is correct. These are two complete sentences, so option 3 is definitely correct. Option 4 has a sentence that has two complete sentences joined together without any puncuation, which is incorrect, so Options 2 and 3 are correct.
The correct answer is B. The first sentence refers to a general proposition - <em>all combative sports should be strictly monitored</em> - and then it specifies that the Ultimate Fighting Championship (UFC) should fall into a category to be <em>monitored and regulated</em>.