Following Nightblade354 advise to push my CR skills beyond the limits, I'll post an extensive analysis of this question, explaining the initial thoughts on the stimulus and the reasons why I reject four options and choose one as the winner

. I beieve this is one of the best ways to improve in CR. Don't just do questions, but try to extract as much as possible from each of them. I think doing blind review help a lot in doing so (more about blind review here:
https://gmatclub.com/forum/mod-nightbla ... 95316.html)
Here is the stimulus: Astrophysicist:
Gamma ray bursts (GRBs) -explosions of powerful radiation from deep space - have traditionally been classified as either "short'' or "long," terms that reflect the explosion's relative duration. However, an unusual GRB has been sighted. Its duration was long, but in every other respect it had the properties of a short GRB. Clearly, the descriptive labels "short" and "long" have now outlived their usefulness. 1º Premise: GRBs classified as short/long. This defines duration
2º Premises: Unusual GRB spotted. it was a long one but with the characteristics of a short
Conclusion: short-long labels should be over
Initial thoughts: GRBs have been classified as short or long because it is the term that defines how long the GRB is. But wait, why should they be classified by duration. Is it the only difference between the two types? Not only difference, but the most important one perhaps? mmm. I don't know, let's keep reading. mmm ok. I understand now. There are more properties as to which GRBs are defined, but durations seems to be the most important one. They saw a GRB whose duration was long, but all the other properties were short. OK. So I understand that the conclusion is that GRBs should be classified not in terms of duration.
But wait. What if the one spotted was an outlier? What if 99.9% of GRBs should be classified as short-long because this classifications works? An outlier should break down the terminology that GRBs used to have? mmm I don't think so. The option should give me a good reason why this terminology should be over. Maybe they discovered that other properties are more important or that are able to differentiate better the two types of GRBs. This should be enough. Let's read options having this in mind.(A) No other GRBs with unusual properties have been sighted.No other unusual GRBs have been sigthed. Ok, fair enough. This sounds good. This argument says that this is an outlier and could indicate that labels are still good. But hey!. We want actually the opposite. We want to steghtne the argument why the labels should be different and not why they should still be the same. So this is Weakness!.
Incorrect(B) The classification of GRBs can sometimes be made on the basis of duration alone.This option weakens the argument. If the classification should be made on the basis of duration alone, why would the author conclude the opposite?
Incorrect(C) Properties other than duration are more important than duration in the proper classification of the unusual GRB.I like this one. It says that other properties are more important. If so, definitely, the author is right in saying that the short-long labels are over!. This is definitely more assertive than option A)!.
Keep it!(D) GRBs cannot be classified according to the different types of cosmic events that create them.This is out of scope. It doesn't address why the short/long labels should be over.
Incorrect(E) Descriptive labels are easily replaced with nondescriptive labels such as "type I'' and "type II."Non descriptive? But I think we want labels that describe the different GRBs.
Option C is much much betterOPTION C