Let the radius of the cylindrical tank be ' $$r$$ ' inches.

It is known that the water rises 0.1 inches/min which is equal to the height of the cylindrical tank.

We know that water runs in the cylindrical tank at the rate of 1000 cubic inches/min, so we get volume of the cylindrical tank $$\pi r^2 h=1000 \quad$$ i.e. $$\pi \times r^2 \times 0.1=1000 \Rightarrow r=\sqrt{1000 \times \frac{1}{\pi } \times \frac{1}{0.1}}=$

$\frac{100}{\sqrt{\pi}}$$ inches

Hence the answer is (C).