Unlike the other major planets, Pluto has a highly eccentric orbit, which is thus closer to the Sun than Neptune is for 20 years out of every 230-year cycle, even though it is commonly described as the remotest planet in the solar system.

A) Pluto has a highly eccentric orbit, which is thus closer to the Sun than Neptune is -which is wrongly modifying orbit
B) Pluto has a highly eccentric orbit and is thus closer to the Sun than Neptune is -Correct
C) Pluto's orbit is highly eccentric and is thus closer to the Sun than Neptune -1. incorrect comparison between planets and orbit 2.meaning change
D) the orbit of Pluto is highly eccentric and thus closer to Sun than Neptune -1. incorrect comparison between planets and orbit 2.meaning change
E) the orbit of Pluto is highly eccentric, thus closer to the Sun than Neptune is -1. incorrect comparison between planets and orbit 2.meaning change 3.
incorrect comparison between orbit and neptune
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Unlike the other major planets, Pluto has a highly eccentric orbit, which is thus closer to the Sun than Neptune is for 20 years out of every 230-year cycle, even though it is commonly described as the remotest planet in the solar system.

A) Pluto has a highly eccentric orbit, which is thus closer to the Sun than Neptune is
B) Pluto has a highly eccentric orbit and is thus closer to the Sun than Neptune is
C) Pluto's orbit is highly eccentric and is thus closer to the Sun than Neptune
D) the orbit of Pluto is highly eccentric and thus closer to Sun than Neptune
E) the orbit of Pluto is highly eccentric, thus closer to the Sun than Neptune iss[/quote]

I am not clear about such a rule. If they cannot be connected by 'and' what else is the connector?

Why do you think the cause and effect can be both be nouns but not parallel and thus cannot be connected by an 'and'?

The injury was just a scratch and thus the treatment was only a band-aid bandage

He passed out after a couple of pegs and vomited profusely. Passed out was the cause and vomited is the result, both of them perfectly parallel.

Probably you are getting confused with the sentence structure wherein the cause is represented by an IC while the effect is represented by a modifier. AS the modifier spot unlikely to be a, you may feel the effect part is a fragment on the whole.

But please note that Choice B is a simple sentence with tow predicates. The second one is not an IC, It is a predicate without a subject and the subject of the first class is the subject of the second predicate.

Hope I am clear and you are also clear.
Thanks
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Unlike the other major planets, Pluto has a highly eccentric orbit, which is thus closer to the Sun than Neptune is for 20 years out of every 230-year cycle, even though it is commonly described as the remotest planet in the solar system.

A) Pluto has a highly eccentric orbit, which is thus closer to the Sun than Neptune is
B) Pluto has a highly eccentric orbit and is thus closer to the Sun than Neptune is
C) Pluto's orbit is highly eccentric and is thus closer to the Sun than Neptune
D) the orbit of Pluto is highly eccentric and thus closer to Sun than Neptune
E) the orbit of Pluto is highly eccentric, thus closer to the Sun than Neptune is
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