Answer:
Option A -

Explanation:
Given : A group of students is given a 10 by 10 grid to cut into individual unit squares. The challenge is to create two squares using all of the unit squares. Their teacher states that after the two new squares are formed, one should have a side length two units greater than the other.
To find : Which equation represents x, the side length of the greater square?
Solution :
Let x be the side of the larger square.
We have given that 'one should have a side length two units greater than the other'.
So, the side length of other smaller square is (x-2).
The challenge is to create two squares.
- The number of unit squares included in the larger square is

- The number of unit squares included in the smaller square

- A group of students is given a 10 by 10 grid to cut into individual unit squares is

This all represent the equation

Therefore, Option A is correct.