The angle between vectors $\vec a$ and $\vec b$ is $\frac{\pi }{6}$. The angle between vectors $ - 3\vec a$ and $ 2\vec b$ is

  • A

    $\frac{\pi }{3}$

  • B

    $\frac{\pi }{2}$

  • C

    $\frac{7\pi }{6}$

  • D

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

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