$A$ student can distinctly see objects up to a distance of $15 \, cm$. He wants to see the blackboard at a distance of $3 \, m$. The focal length and power of the lens used,respectively,will be:

  • A
    $ - 4.8 \, cm, - 3.3 \, D$
  • B
    $ - 5.8 \, cm, - 4.3 \, D$
  • C
    $ - 7.5 \, cm, - 6.3 \, D$
  • D
    $ - 15.8 \, cm, - 6.3 \, D$

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