The following sentence has a dangling modifier.
after reading the book it was based on, several key plot elements were missing from the mou
which revision best corrects the error in this sentence?
several key elements were missing from the movie, i noticed, after i read the book it was
i noticed that several key plot elements were missing from the movie after i read the bool
after reading the book that the movie was based on, i noticed that the movie was missing
i noticed, after i read the book it was based on that several key plot elements were missi

The revision that best corrects the error in the sentence is the following one: I noticed that several key plot elements were missing from the movie after I read the book.

Explanation:

A dangling modifier is a word or phrase that modifies a word not clearly stated in the sentence. In the original sentence, the participle "after reading the book it was based on" does not include the word/phrase it modifies, making the sentence sound odd. Therefore, the revision should include said word or phrase.

The best version of the sentence is the one chosen because it is correctly punctuated and it does not sound odd. Moreover, it includes all the information of the original sentence. The information included in the present participle is now an adverb clause of time (after I read the book) and thus the problem has been solved. The new version of the sentence also makes explicit the doer of the action, that is, the person doing the reading (I). The dangling modifier version made it look as if the one doing the reading was "several key plot elements".