Let $S$ be the set of all values of $a_1$ for which the mean deviation about the mean of $100$ consecutive positive integers $a _1, a _2, a _3, \ldots ., a _{100}$ is $25$. Then $S$ is

  • [JEE MAIN 2023]
  • A

    $\phi$

  • B

    $\{99\}$

  • C

    $N$

  • D

    $\{9\}$

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