GMAT Critical Reasoning (CR) | Astronomer: Observations of the Shoemaker-Levi comet on its

Lets break the argument-
Getting the estimate of the Size is the goal so anything accomplishing that would be the Conclusion. Now,lets follow the premises,one by one, leading to the conclusion.
1. Analyses found sulfur in the Outer Layer
2.The fragments contained no sulfur (so, it is to good to think that Sulfur is either in outer or inner layer)
3. Yes, it is inner atmosphere that contains sulfur. Sulfur would have seeped into the outer layer. For that to happen it is necessary that
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