ambiguous pronoun and modifier

[manhhiep2509]

Hello.

The OG says choice C in question 75 of review verbal 2 is incorrect because "Its does not have a referent".
I guess "referent" means to a noun, isn't it?
"Baltic Sea" is an adjective, so "Its" cannot refer to "Baltic Sea".

I made the below sentence up, but I saw some correct sentences in OG have the same structure.

John's new novel is interesting, but his new poem is very boring.

"John's" is not a noun but an adjective, and "his" could refer to a noun "John".
Why is the sentence correct? what is the difference between the two sentences?
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OG explanation says choice E in the same question is incorrect because "consistent illogically describes the Baltic Sea."

It seems that adjective phrase, such as "consistent with ....", cannot refer to entire preceding sentence even though the phrase is separated from the preceding clause by "a comma".
Is it correct?

Thank you.

[RonPurewal]

I made the below sentence up, but I saw some correct sentences in OG have the same structure.

John's new novel is interesting, but his new poem is very boring.

"John's" is not a noun but an adjective, and "his" could refer to a noun "John".
Why is the sentence correct? what is the difference between the two sentences?

"John's" stands exactly for "his". If's certainly ok for its/his/her(s)/their(s) to stand for the exact possessive that's already there.

On the other hand, when you have a noun used as an adjective with no possessive qualities at all (e.g., California highways) then there's nothing for an "its" (or "it", for that matter) to stand for.

[RonPurewal]

It seems that adjective phrase, such as "consistent with ....", cannot refer to entire preceding sentence even though the phrase is separated from the preceding clause by "a comma".
Is it correct?

Adjectives describe nouns.

Even if they are separated by commas, they still must describe nouns. Not whole actions.