Cool question, but not that difficult.

First figure out what the question is asking: phrase it in your own words. If you cut away all the BS, you end up with "what do Carolyn and Arnold actually disagree about?"

What indeed? Carolyn presents the object and says that the artist calls it a portrait. She then goes to show voice her concern: to be a portrait, it must bear recognizable resemblance. This objection sums up Carolyn's position: Since the DNA apparently bears no recognizable resemblance to Sulton, it is not a portrait.

Arnold disagrees by saying that the conceptual portrait is a portrait - and that is the point of disagreement between the two: Whether this DNA is a portrait or not. The answer is E.

The only dangerous answer choice that I see is C, but whether the DNA resembles Sulton or not is not contested by Arnold. Arnold isn't saying "you're wrong - this fragment of DNA DOES resemble Sulton". What Arnold is saying that the DNA can be used to recreate Sulton, but not that it resembles him in its sorry, present state.

Thanks Geva, the answer is in fact E, I guessed C would trick a few people , so thought of posting the question.

This is a lower level LSAT prob.