When a telescope is adjusted for parallel light,the distance of the objective from the eyepiece is found to be $80 \,cm$. The magnifying power of the telescope is $19$. The focal lengths of the lenses are
- A$61 \,cm, 19 \,cm$
- B$40 \,cm, 40 \,cm$
- C$76 \,cm, 4 \,cm$
- D$50 \,cm, 30 \,cm$
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