Answer:
1. Since you have to square the number of units to use the Pythagorean theorem, the dashes represent the number you would use in the equation(without squaring afterwards) . So if its 3 units long, there are 9 dashes. (3^2=9)
2. You can't use the number of boxes because that wouldn't give you the correct answer for C, since all of the variables have to be squared first for the formula to work.
Explanation: