The answer is B because it doesn't have any commas and it wouldn't make sense without it. Looks like you got it correct.
The initial results seemed promising, but the final effects were kind of disappointing.
In the given sentence above, the unnecessary qualifier that needs to be removed is "kind of". It is an informal expression which is usually used as meaningless fillers. So, the final sentence will be:
The initial results seemed promising, but the final effects were disappointing.
Sorry I don’t quite get the question. Could you rephrase it?
