PrepTest 136, Section 4, Question 17
Although Pluto has an atmosphere and is much(36 more words not shown)
The conclusion of the argument(10 more words not shown)
- ANo celestial body(8 more words not shown)
- BNot all celestial(12 more words not shown)
- CIf Pluto had(24 more words not shown)
- DThe size of(21 more words not shown)
- EFor a celestial(16 more words not shown)
Reading the argument
What makes something a true planet? An atmosphere and a large size do not settle that question here. The author dismisses Pluto based on where it formed, but has not supplied a definition connecting that history to its present classification.
Accept the stated history for this argument: Pluto formed in orbit around Neptune and was later ejected from that orbit. Why would that prevent it from being a planet now? We need a rule saying that having formed around another planet disqualifies a body from being a true planet.
What we’re looking for
The question asks us to make the conclusion follow. A rule that merely allows some bodies to fall outside the planet category is too weak. We need one that specifically excludes a body with Pluto's stated history.
Working the answers
- A
This prevents something from being a moon and a planet at the same time. The argument describes Pluto's former orbit around Neptune and its later ejection. A restriction on simultaneous classifications does not establish that something formerly orbiting another planet can never become a planet itself.
- B
This allows exceptions: some bodies with atmospheres that orbit the sun are not true planets. But which ones? It does not establish that Pluto is among the exceptions. The conclusion needs a rule that settles Pluto's case, not one that leaves its status open.
- C
This describes what would have happened if Pluto had not been ejected. The argument says it was ejected. Knowing that it would otherwise still be a moon does not tell us whether, given its actual history as described, it now qualifies as a planet.
- D
Removing size from consideration does not tell us what the relevant requirements are. Even if size is irrelevant, Pluto might qualify for some other reason. We need a condition it fails, not just one feature we may ignore.
- ECorrect
A true planet must have formed in orbit around the sun exclusively. Pluto formed in orbit around Neptune, so its formation does not meet that requirement. This connects the stated history to the conclusion that Pluto is not a true planet, exactly as the argument needs.
More Sufficient Assumption questions
Learn the LSAT our way
Our platform drills Sufficient Assumption questions at your level and adjusts as you improve.