If $2y\,\cos \theta = x\sin \,\theta {\rm{ and }}2x\sec \theta - y\,{\rm{cosec}}\,\theta = 3,$ then ${x^2} + 4{y^2} = $

  • A

    $4$

  • B

    $-4$

  • C

    $± 4$

  • D

    None of these

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