Sentence 1a is ungrammatical since and is a co-ordinating conjunction and thus there should be a finite verb/main verb after the subject (the other) of the clause. Instead of that, there is a relative pronoun (which)! Sentence 1b is technically grammatical as the of which structure is repeated after and.
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Cool BreezeSentence 1a is ungrammatical since and is a co-ordinating conjunction and thus there should be a finite verb/main verb after the subject (the other) of the clause. Instead of that, there is a relative pronoun (which)!