To improve the clarity and development of ideas in sentence 10, the best revision is:
C. Not only does this impact their academic performance, but it also affects their ability to engage in meaningful real-world interactions and activities.
This option enhances clarity by using a more engaging and structured "not only... but also" construction, which emphasizes the dual impact being discussed. Additionally, it provides a smoother flow to the sentence and highlights the significance of both aspects (academic performance and real-world engagement).