The square root of 0.342 × 0.6840.000342 × 0.000171 = ?

Answer: Option C

$$\begin{array}{rl}& \text{According to the question,}\\ & \sqrt{\frac{0.342\times 0.684}{0.000342\times 0.000171}}\\ & =\sqrt{\frac{342\times 684\times 1000000}{342\times 171}}\\ & =\sqrt{4\times 1000000}\\ & =2\times 1000\\ & =2000\end{array}$$