6. If point $P$ is on the parabola $y^{2}=x$, and point $Q$ is on the circle $(x-3)^{2}+y^{2}=1$, then the minimum value of $|P Q|$ is
A. $\sqrt{3}-1$
B. $\frac{\sqrt{10}}{2}-1$
C. 2
D. $\frac{1}{2}(\sqrt{11}-2)$
6. D Hint: It is evident that such points $P, Q$ must pass through the circle center $(3,0)$, thus the problem is converted to finding the minimum distance from a point on the parabola to $(3,0)$.



保留源文本的换行和格式，翻译结果如下：

6. D Hint: It is evident that such points $P, Q$ must pass through the circle center $(3,0)$, thus the problem is converted to finding the minimum distance from a point on the parabola to $(3,0)$.

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Note: The translation preserves the original formatting and structure of the text.