If the position vectors of $P$ and $Q$ are $\hat{i}+2 \hat{j}-7 \hat{k}$ and $5 \hat{i}-3 \hat{j}+4 \hat{k}$ respectively,then the cosine of the angle between $\overrightarrow{PQ}$ and $z$-axis is

  • A
    $\frac{4}{\sqrt{162}}$
  • B
    $\frac{11}{\sqrt{162}}$
  • C
    $\frac{5}{\sqrt{162}}$
  • D
    $\frac{-5}{\sqrt{162}}$

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