If 5 spiders can catch five files in five minutes, how many files can hundred spiders catch in 100 minutes ?

Answer: Option D

Let the required number of chairs be x.
Then, More spiders, More flies (Direct proportion)
More time, More flies (Direct proportion)
$$\begin{array}{c}\text{Spiders 5}:100\text{hfill}\\ \text{Minutes 5}:100\text{hfill}\end{array}\}::5:x$$
$$\begin{array}{rl}& \therefore 5\times 5\times x=100\times 100\times 5\\ & \iff x=\frac{\left(100\times 100\times 5\right)}{\left(5\times 5\right)}\\ & \iff x=2000\end{array}$$