In a school with $600$ students, the average age of the boys is $12$ $years$ and that of the girls is $11\, years.$ If the average age of the school is $11 \,years$ and $9 \,months,$ then the number of girls in the school is

  • A

    $450$

  • B

    $150$

  • C

    $250$

  • D

    $350$

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