The change that was made in the second sentence is the sentence length. The initial sentence is actually a compound one that contains two independent clauses joined by a comma. Therefore, omit the last option. The position of subject and verb in a sentence did not change at all, the only thing that makes difference now is that sentence has been divided into two new ones. So the third option does not make sense too. And, all in all, there is no prepositional phrases, which means that the length made the whole change :)