Why is E incorrect?

I want to make sure you my reasoning for this type of question is correct. In order for this question to be correct, the answer must make a valid conclusion and it must be a conclusion that can only be drawn using premises/facts from BOTH passages. This means an incorrect answer choice could be a valid conclusion, however, if it is a conclusion that can be made using only one passage, even if it contains support in both passages, it is not the right answer choice. This is why E is incorrect since the opening of passage B allows you to make this conclusion without any support from A, even thought it is a valid conclusion. "cuttings, and associated chemicals . are normally released only during the drilling phase of . a well's existence. These discharges are the main . environmental concern in offshore oil production" Is my understanding of this question type in general, and why E is incorrect the right line of thinking?