Let $\theta, 0 < \theta < \pi / 2$, be an angle such that the equation $x ^2+4 x \cos \theta+\cot \theta=0$ has equal roots for $x$. Then $\theta$ in radians is

  • [KVPY 2021]
  • A

    $\frac{\pi}{6}$ only

  • B

    $\frac{\pi}{12}$ or $\frac{5 \pi}{12}$

  • C

    $\frac{\pi}{6}$ or $\frac{5 \pi}{12}$

  • D

    $\frac{\pi}{12}$ only

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