Help me answer this practice multiple choice question. make sure to list the equations you use: "The eyepiece for the Yerkes telescope has a focal length of approximately $10$ cm$.$ The Hubble Space Telescope can reach an effective angular magnification factor of $8000.$ What would the focal length of the objective lens at Yerkes need to be in order to reach the same factor of $8000?"$

A$)80$ m

B$)0\mathrm{.}125$ m

C$)8$ m

D$)0\mathrm{.}00125$ m

E$)800$ m