The correct answer for the given question above would be option D. on the other team. This is the prepositional phrase used in the sentence. A prepositional phrase is defined as a group of words consisting of a preposition and its complement. The preposition used in this phrase is the word "on".
The sentence that contains a faulty parallel structure; I suggest that you take additional courses and working on a theoretical project. The correct answer is B.
I would say that it hasn't increased 20% because 1. if the starting percentage was 18%, you would see a larger precentage but that isn't the case.