OFFICIAL EXPLANATION
In figure skating, scores are based on expression, precision and innovating tricks.A. expression, precision and innovating
This answer choice is grammatically incorrect. The list in the original sentence contains items that are not of the same part of speech. The nouns expression and precision do not parallel the verb innovating.
What helps us identify this question as a Parallelism question as well as identify the mistake is the following Stop Sign: A list of 3 items or more, separated by commas and and/or before the last item.
So in this answer innovating (tricks) is a gerund/action. And while it is possible to have an 'ing' as an adjective (eg the ringing bells are loud) here the natural adjective for the word innovation is innovative not innovating. Had innovative not been there as an answer choice, it would have possibly been correct as an ing adjective.B. expression, precision and to innovate
This answer choice repeats the original Parallelism mistake. The list contains items that are not of the same part of speech. The nouns expression and precision do not parallel the verb to innovate.C. the expression, precision and innovation of
Although this answer choice corrects the original mistake and is grammatically correct, it creates a change in meaning. In the original sentence, the words expression and precision are not linked to tricks whereas in this answer choice they are.D. expression, precision, and innovative
The list in the original sentence contains items that are not of the same part of speech. The nouns expression and precision do not parallel the verb innovating.
This answer choice corrects the mistake by changing the sentence so that the third item on the list is a noun as well (innovative new tricks).E. expression, precision, or innovative
Although this answer choice corrects the original mistake and is grammatically correct, it changes the meaning of the original sentence by replacing and with or.