TSA 2017 Q32 (Logic)

Hi. I don’t quite understand what this question is referring to, I would appreciate any tips on how I should approach this question. Thank you in advance!

Text:
32 Instructions were given to shade 5 particular squares on a grid of 16 squares. One student shaded in the squares as instructed, but the other four got exactly 1 square wrong.
Which one of the five grids below shows the correct shading?

Correct Answer: Option E