TOEFL Listening: TPO-TOEFL阅读TPO - 31T4C9_JO4EF584QN$

Why does the author mention "a telescope" as part of the discussion of microscopes? A. To show how microscopes and telescopes are different B. To emphasize the importance of magnification in all optical devices C. To explain how he development of the microscope depended on the invention of the telescope D. To illustrate the concept of resolving power