We are looking for a word with a negative tone that describes someone who is slowing something down because they won’t agree with the rest of the group. (A) is exactly what we’re looking for here.

The juror in this sentence is slowing things down because they won’t agree with the rest of the jury. There is nothing to indicate that this single juror is suspicious, just that they are preventing a unanimous verdict. Because of this, (B) is unsupported.

Being careful is a positive trait for jurors, but in the sentence we’re looking at, critics say that the unanimity requirement slows things down too much. Because of this, we know that the critics aren’t complementing this single juror for being careful.

Being a conscientious juror is a good thing, but in the sentence we’re looking at, critics say that the unanimity requirement slows things down too much. This shows us that, in the context of this sentence, we aren’t looking for a word with a positive tone.

This doesn’t make sense in the context of the sentence. In the sentence, the critics say that one single juror is forcing a retrial because they won’t agree with the rest of the jury. There is nothing to indicate that this single juror is clueless, so (E) is unsupported.