You Have a Choice Between Two Lenses of Focal Lengths $M _ { b } = M _ { a } / 4$

Multiple Choice

You have a choice between two lenses of focal lengths fa and fb, where fb = 2fa, to use as the objective lens in building a refracting telescope. If the magnification you obtain using lens a is Ma,
What will be the magnification when using lens b?

A) $M _ { b } = M _ { a } / 4$
B) $M _ { b } = 2 M _ { a }$
C) $M b = 8 M _ { a }$
D) $M _ { b } = 4 M _ { a }$
E) $M _ { b } = M _ { a } / 2$