Although Pluto has an atmosphere and is much larger than any asteroid, Pluto is not a true planet. Pluto formed in orbit around the planet Neptune and was then ejected from orbit around Neptune when Triton, Neptune's largest moon, was captured by Neptune's gravity.

The conclusion of the argument follows logically if which one of the following is assumed?

(A) No celestial body can simultaneously be a moon and a planet.
(B) Not all celestial bodies that have an atmosphere and orbit the sun are true planets.
(C) If Pluto had not been ejected from its orbit around Neptune, Pluto would not have its current orbit around the sun and would still be a moon.
(D) The size of a celestial body in orbit around the sun is not relevant to determining whether or not it is a true planet.
(E) For a celestial body to be a true planet it must have formed in orbit around the sun exclusively.

Source: LSAT
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Non progredi est regredi

hi..
reason why C and other choices are incorrect and E is correct..

(A) No celestial body can simultaneously be a moon and a planet.
pluto is NOT both moon and planet.... so out

(B) Not all celestial bodies that have an atmosphere and orbit the sun are true planets.
conclusion itself says that pluto has an atmosphere and if you negate this doesnt help the reasoning

(C) If Pluto had not been ejected from its orbit around Neptune, Pluto would not have its current orbit around the sun and would still be a moon.
SO WHAT!!! we are talking of WHY Pluto is not a true planet although it has the characteristics of a planet. and this doesn't help in it at all.

(D) The size of a celestial body in orbit around the sun is not relevant to determining whether or not it is a true planet.
Size is mentioned in conclusion but not a criteria in reasoning

(E) For a celestial body to be a true planet it must have formed in orbit around the sun exclusively.
"Pluto formed in orbit around the planet Neptune and was then ejected from orbit around Neptune" is mentioned and then it is said that Pluto is not a planet. so it means any celestial body not formed in orbit around sun from very beginning is not to be considered a planet ... TRUE

E
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1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


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