Here are the most effective revisions for each of the sentences you provided:
14. What is the MOST effective way to revise this sentence?
B. As students learn how to be good mentors, they focus on effective communication skills, including how to share and how to listen.
(This option removes redundancy while retaining clarity.)
18. What change, if any, needs to be made in sentence 2?
D. No change should be made in sentence 2.
(The sentence is grammatically correct as it stands.)
19. What is the correct way to write sentence 23?
D. Our high school has an opportunity to allow its students to influence the future today, and it should do so by starting a mentoring program.
(This option adds a necessary comma before "and" to improve clarity.)
20. What change needs to be made in sentence 8?
B. Her classroom is crowded, and she can’t always get the one-on-one attention that she needs to understand a new concept.
(This revision corrects the run-on sentence by adding a comma before "and.")