Looks like you are working from the text that goes with our Weekend course. What threw us off was the reference to Lesson 4 - in most versions of the course book, it's not broken down into lessons in that way. I'm on the same page with you now, though (well, almost - in my edition of the book that question is actually on page 116
First, just to be clear, the correct answer to Question 7 for RC Passage 1 from June 1995, the passage about the various theories for the extinction of the dinosaurs, is B, not E. That answer is essentially a "cause without effect" answer. If the volcanic eruption theory is based partially on the idea that a diaper eruption would have released large amounts of CO2 into the atmosphere, causing climatic changes that lead to mass extinctions, then we would expect any such eruption to do the same thing. If B is true - most such eruptions did not lead to climatic changes - that would weaken the argument in favor of the volcanic eruption theory by showing that sometimes the alleged cause occurs and the supposed effect does not.
E is basically irrelevant - it doesn't matter that marine species are more vulnerable to sudden than to gradual changes. The facts are known - the sea level changed gradually, and the marine species went extinct over time. A sudden change might have been worse for them, but that doesn't mean a gradual change wasn't sufficient to do the job. Look at it this way - what if we said that dinosaurs would have been more vulnerable to a global nuclear attack by hostile aliens than to a volcanic eruption? Would that weaken the theory that volcanic eruption was the cause? Of course not - the known facts still fit the offered theory just fine, notwithstanding what might have been worse.
Hope that helps! Best of luck!
Adam M. Tyson
PowerScore LSAT, GRE, ACT and SAT Instructor
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